Answer Key
I. Multiple choices (2 pts each)
1. A
2. D
3. B
4. B
5. B
6. A
7. A
8. D
9. E
10. B
11. C
12. C
13. B
14. B
15. D
16. D
17. E
18. C
19. A
20. A
21. C
22. D
23. C
24. B
25. B
II. PROBLEMS’ FINAL ANSWERS (10 pts each)
1. (b) Rx = -1618.05 km
Ry = 801.72 km
R=1805.78 km
Direction: 26.36 degrees North of West
2. (a) 21.28 m
(b) 20.64 m/s
3. (c) 0.49 m/s^2
4. vx = -19.67 km/h
vy = 6.89 km/h
v = 20.84 km/h
direction: 19.30 degress North of West
5. (a) v = 2.99 x 10^4 m/s
(b) Equate the centripetal force to the gravitational force exerted by the Sun on the Earth. Your equation should look like this
mv^2/R=GmM/R^2
Where M is the Sun’s mass, m is the mass of the earth, and R is the radius of Earth’s orbit.
M = 2.01 x 10^30 kg
Friday, April 29, 2011
Phys 11 Self Test (Prelim Coverage)
SaLam and Good Evening!
The following is a self test to help you test your understanding of our topics. Please take note that blogger.com does not provide any option to write subscript or exponent. So writing subscripts and exponents here, I made the following notations:
^ means raised to the power of (exponent)
* means subscript.
Example:
v^2 means variable v is squared
vx or v*x means the variable v has subscript x
Test yourselves to know how much you do really know. You should be able to finish this test within 2 hours. I suggest you to follow this time limit. I have also uploaded the answer key to this self test on another post. If you find some errors, please let me know asap. Good luck.
I. MULTIPLE CHOICES. Direction: Choose the best choice. Just write the letter corresponding to your choice. In some questions there can be more than one answer. But choose only the best one.
1. Which of the following quantities is NOT a vector?
A. Mass
B. Displacement
C. Weight
D. Acceleration
E. Force
2. A newton is the force:
A. of gravity on a 1 kg body
B. of gravity on a 1 g body
C. that gives a 1 g body an acceleration of 1 cm/s^2
D. that gives a 1 kg body an acceleration of 1m/s^2
E. that gives a 1 kg body an acceleration of 9.8m/s^2
3. The term “mass” refers to the same physical concept as:
A. weight
B. inertia
C. force
D. acceleration
E. volume
4. Mass differs from weight in that:
A. all objects have weight but some lack mass
B. weight is a force and mass is not
C. the mass of an object is always more than its weight
D. mass can be expressed only in the metric system
E. there is no difference
5. A block moves with constant velocity on a horizontal surface. A horizontal force of magnitude 5 N to the right is exerted on the block. Another horizontal force of magnitude 3 N to the left is exerted on the same block. The frictional force is:
A. 0
B. 2N, leftward
C. 2N, rightward
D. slightly more than 2N, leftward
E. slightly less than 2N, leftward
6. A 6-kg object is moving south. A net force of 12N north on it results in the object having an
acceleration of:
A. 2m/s^2, north
B. 2m/s^2, south
C. 6m/s^2, north
D. 18m/s^2, north
E. 18m/s^2, south
7. A 400-N steel ball is suspended by a light rope from the ceiling. The tension in the rope is:
A. 400N
B. 800N
C. zero
D. 200N
E. 560N
8. In the formula F = *Gm*1m*2)/r^2, the quantity G:
A. depends on the local value of g
B. is used only when Earth is one of the two masses
C. is greatest at the surface of Earth
D. is a universal constant of nature
E. is related to the Sun in the same way that g is related to Earth
9.The magnitude of the acceleration of a planet in orbit around the Sun is proportional to:
A. the mass of the planet
B. the mass of the Sun
C. the distance between the planet and the Sun
D. the reciprocal of the distance between the planet and the Sun
E. the product of the mass of the planet and the mass of the Sun
10. A horse exerts a force F on a cart, causing the cart to move with increasing speed. What force does the cart exert on the horse?
a) zero
b) equal to the magnitude of F
c) greater than F
d) less than F
e) cannot be determined unless the acceleration is given
11. When an object is in uniform circular motion,
A. the velocity of the object is constant
B. the acceleration of the object is constant
C. the rate of revolution is constant
D. the force acting on the object is constant
For items 12 – 13, consider the following situation: “A car of mass 1200 kg, moving with a speed of 60 km/hr round a highway curve of radius 200-m. The road bed is level and flat.”
12. The central force needed for the car to successfully round the curve is roughly
A. 11,760 N B. 9,667 N C. 1,667 N D. 969.7 N
13. The coefficient of static friction between the road and tires of the car is roughly
A. 0.082 B. 0.142 C. 0.822 D. 0.100
14. Cart A has a mass of 2 kg and a speed of 3 m/s. Cart B has a mass of 3 kg and a speed of 2 m/s. Compared to the magnitude of momentum of cart A, cart B has __.
A. smaller magnitude of momentum
B. the same magnitude of momentum
C. greater magnitude of momentum
D. not enough information to tell
15. A 0.2-kg ball slides across a frictionless floor with a speed of 10 m/s. If the ball strikes a wall and bounces off with a speed of 10 m/s into opposite direction. The magnitude of the impulse on the puck is ___.
A. 0 kg m/s
B. 1 kg m/s
C. 2 kg m/s
D. 4 kg m/s
E. none of the above
16. A small compact PD cab is traveling north on Peace Boulevard with momentum p*A. At the intersection of Peace Boulevard and 4th street it collides with an Armak Jeepney, traveling with momentum p*B. Treating each vehicle as a particle, the magnitude of total momentum before collision ___.
A. p*A+p*B
B. p*A-p*B
C. p*A^2+p*B^2
D. Square root of (p*A^2+p*B^2)
17. You throw your cellphone vertically upward with a velocity of 4 m/s. What is its speed at the highest point it can reach?
A. 4 m/s
B. 2 m/s
C. 1 m/s
D. 9.8 m/s
E. 0
18. Which of the following is a scalar quantity?
A. momentum
B. velocity
C. distance
D. acceleration
19. Consider a rock is thrown upward at an angle. It continues to move under the influence of gravity alone. What happens to the vertical component of its velocity as it rises along its curved path?
A. decreases
B. increases
C. stays the same
D. can not be determined
20. The sluggishness or apparent resistance an object offers to changes in its state of motion.
A. Inertia B. acceleration C. mass D. speed
21. Which of the following is true?
A. If the object is moving with constant velocity, the acceleration is increasing.
B. If the object is moving with constant acceleration, the velocity is constant.
C. If the object is moving with constant acceleration, the velocity is changing.
D. none of the above
22. Which of the following statement(s) is/are true about horizontal component of the velocity of the body in a projectile motion?
A. the horizontal component of the velocity is constant.
B. the horizontal component of its motion is independent of the vertical component.
C. the horizontal component of the velocity is constantly decreasing.
D. A & B.
E. none of the above
For 23-24. You were driving a truck in your very vast hacienda. And then suddenly, you discovered the brake is not working. So in order for you to stop you need to hit something: a haystack or a concrete wall.
23. In which situation would the change in your (you and the truck considered as one body) momentum greater?
A. hitting the haystack B. hitting the concrete wall
C. the same amount of change in momentum in either way
D. can not be determined
24. In which situation would you feel greater force?
A. hitting the haystack
B. hitting the concrete wall
C. the same amount of force in either way
D. can not be determined
25. An object moving in a circular path with constant speed has:
A. zero acceleration because the speed is constant
B. a nonzero acceleration because its direction continuously changes
C. not enough information to tell.
PROBLEM SOLVING
1. An airplane flies 1 000 km in a direction 25 degrees west of north from Miami to Atlanta and then 1 200 km in a direction 5 degrees south of wet to Dallas-Fort Worth. Find the net displacement from Miami to Dallas-Fort Worth: (a) using graphical method (scale 1 cm = 200 km)
(b) using component method
2. A rock is thrown down and falls freely into a well with an initial speed of 3.0 m/s. The rock hits the bottom 1.8 s later. (a) How deep is the well (b) What is the rock’s speed as it hits the bottom?
3. A 20-kg block moves along a horizontal surface with 0.61 coefficient of kinetic friction. The block is pulled by a rope that exerts a 162-N tension force at a 37 degrees angle above the horizontal (a) Draw a free body diagram for the block. (b) Write the Second Law of Motion in component form for each axis (c) Solve the equation to find the crate’s acceleration.
4. A 2100-kg sports car traveling North at 20 mi/h has a head-on collision with a 4000-kg station wagon traveling west at 30 mi/h. If the vehicles remain locked together, what is their final velocity (solve the magnitude and describe its direction) ?
5. The average radius of the earth’s orbit around the sun is 1.5 x 10^8 km. The mass of the earth is 5.98 x 10 ^24 kg, and it makes one revolution in 365 days. (a) Calculate the speed of the earth. (b) Calculate the sun’s mass using the Universal law of gravitation.
The following is a self test to help you test your understanding of our topics. Please take note that blogger.com does not provide any option to write subscript or exponent. So writing subscripts and exponents here, I made the following notations:
^ means raised to the power of (exponent)
* means subscript.
Example:
v^2 means variable v is squared
vx or v*x means the variable v has subscript x
Test yourselves to know how much you do really know. You should be able to finish this test within 2 hours. I suggest you to follow this time limit. I have also uploaded the answer key to this self test on another post. If you find some errors, please let me know asap. Good luck.
I. MULTIPLE CHOICES. Direction: Choose the best choice. Just write the letter corresponding to your choice. In some questions there can be more than one answer. But choose only the best one.
1. Which of the following quantities is NOT a vector?
A. Mass
B. Displacement
C. Weight
D. Acceleration
E. Force
2. A newton is the force:
A. of gravity on a 1 kg body
B. of gravity on a 1 g body
C. that gives a 1 g body an acceleration of 1 cm/s^2
D. that gives a 1 kg body an acceleration of 1m/s^2
E. that gives a 1 kg body an acceleration of 9.8m/s^2
3. The term “mass” refers to the same physical concept as:
A. weight
B. inertia
C. force
D. acceleration
E. volume
4. Mass differs from weight in that:
A. all objects have weight but some lack mass
B. weight is a force and mass is not
C. the mass of an object is always more than its weight
D. mass can be expressed only in the metric system
E. there is no difference
5. A block moves with constant velocity on a horizontal surface. A horizontal force of magnitude 5 N to the right is exerted on the block. Another horizontal force of magnitude 3 N to the left is exerted on the same block. The frictional force is:
A. 0
B. 2N, leftward
C. 2N, rightward
D. slightly more than 2N, leftward
E. slightly less than 2N, leftward
6. A 6-kg object is moving south. A net force of 12N north on it results in the object having an
acceleration of:
A. 2m/s^2, north
B. 2m/s^2, south
C. 6m/s^2, north
D. 18m/s^2, north
E. 18m/s^2, south
7. A 400-N steel ball is suspended by a light rope from the ceiling. The tension in the rope is:
A. 400N
B. 800N
C. zero
D. 200N
E. 560N
8. In the formula F = *Gm*1m*2)/r^2, the quantity G:
A. depends on the local value of g
B. is used only when Earth is one of the two masses
C. is greatest at the surface of Earth
D. is a universal constant of nature
E. is related to the Sun in the same way that g is related to Earth
9.The magnitude of the acceleration of a planet in orbit around the Sun is proportional to:
A. the mass of the planet
B. the mass of the Sun
C. the distance between the planet and the Sun
D. the reciprocal of the distance between the planet and the Sun
E. the product of the mass of the planet and the mass of the Sun
10. A horse exerts a force F on a cart, causing the cart to move with increasing speed. What force does the cart exert on the horse?
a) zero
b) equal to the magnitude of F
c) greater than F
d) less than F
e) cannot be determined unless the acceleration is given
11. When an object is in uniform circular motion,
A. the velocity of the object is constant
B. the acceleration of the object is constant
C. the rate of revolution is constant
D. the force acting on the object is constant
For items 12 – 13, consider the following situation: “A car of mass 1200 kg, moving with a speed of 60 km/hr round a highway curve of radius 200-m. The road bed is level and flat.”
12. The central force needed for the car to successfully round the curve is roughly
A. 11,760 N B. 9,667 N C. 1,667 N D. 969.7 N
13. The coefficient of static friction between the road and tires of the car is roughly
A. 0.082 B. 0.142 C. 0.822 D. 0.100
14. Cart A has a mass of 2 kg and a speed of 3 m/s. Cart B has a mass of 3 kg and a speed of 2 m/s. Compared to the magnitude of momentum of cart A, cart B has __.
A. smaller magnitude of momentum
B. the same magnitude of momentum
C. greater magnitude of momentum
D. not enough information to tell
15. A 0.2-kg ball slides across a frictionless floor with a speed of 10 m/s. If the ball strikes a wall and bounces off with a speed of 10 m/s into opposite direction. The magnitude of the impulse on the puck is ___.
A. 0 kg m/s
B. 1 kg m/s
C. 2 kg m/s
D. 4 kg m/s
E. none of the above
16. A small compact PD cab is traveling north on Peace Boulevard with momentum p*A. At the intersection of Peace Boulevard and 4th street it collides with an Armak Jeepney, traveling with momentum p*B. Treating each vehicle as a particle, the magnitude of total momentum before collision ___.
A. p*A+p*B
B. p*A-p*B
C. p*A^2+p*B^2
D. Square root of (p*A^2+p*B^2)
17. You throw your cellphone vertically upward with a velocity of 4 m/s. What is its speed at the highest point it can reach?
A. 4 m/s
B. 2 m/s
C. 1 m/s
D. 9.8 m/s
E. 0
18. Which of the following is a scalar quantity?
A. momentum
B. velocity
C. distance
D. acceleration
19. Consider a rock is thrown upward at an angle. It continues to move under the influence of gravity alone. What happens to the vertical component of its velocity as it rises along its curved path?
A. decreases
B. increases
C. stays the same
D. can not be determined
20. The sluggishness or apparent resistance an object offers to changes in its state of motion.
A. Inertia B. acceleration C. mass D. speed
21. Which of the following is true?
A. If the object is moving with constant velocity, the acceleration is increasing.
B. If the object is moving with constant acceleration, the velocity is constant.
C. If the object is moving with constant acceleration, the velocity is changing.
D. none of the above
22. Which of the following statement(s) is/are true about horizontal component of the velocity of the body in a projectile motion?
A. the horizontal component of the velocity is constant.
B. the horizontal component of its motion is independent of the vertical component.
C. the horizontal component of the velocity is constantly decreasing.
D. A & B.
E. none of the above
For 23-24. You were driving a truck in your very vast hacienda. And then suddenly, you discovered the brake is not working. So in order for you to stop you need to hit something: a haystack or a concrete wall.
23. In which situation would the change in your (you and the truck considered as one body) momentum greater?
A. hitting the haystack B. hitting the concrete wall
C. the same amount of change in momentum in either way
D. can not be determined
24. In which situation would you feel greater force?
A. hitting the haystack
B. hitting the concrete wall
C. the same amount of force in either way
D. can not be determined
25. An object moving in a circular path with constant speed has:
A. zero acceleration because the speed is constant
B. a nonzero acceleration because its direction continuously changes
C. not enough information to tell.
PROBLEM SOLVING
1. An airplane flies 1 000 km in a direction 25 degrees west of north from Miami to Atlanta and then 1 200 km in a direction 5 degrees south of wet to Dallas-Fort Worth. Find the net displacement from Miami to Dallas-Fort Worth: (a) using graphical method (scale 1 cm = 200 km)
(b) using component method
2. A rock is thrown down and falls freely into a well with an initial speed of 3.0 m/s. The rock hits the bottom 1.8 s later. (a) How deep is the well (b) What is the rock’s speed as it hits the bottom?
3. A 20-kg block moves along a horizontal surface with 0.61 coefficient of kinetic friction. The block is pulled by a rope that exerts a 162-N tension force at a 37 degrees angle above the horizontal (a) Draw a free body diagram for the block. (b) Write the Second Law of Motion in component form for each axis (c) Solve the equation to find the crate’s acceleration.
4. A 2100-kg sports car traveling North at 20 mi/h has a head-on collision with a 4000-kg station wagon traveling west at 30 mi/h. If the vehicles remain locked together, what is their final velocity (solve the magnitude and describe its direction) ?
5. The average radius of the earth’s orbit around the sun is 1.5 x 10^8 km. The mass of the earth is 5.98 x 10 ^24 kg, and it makes one revolution in 365 days. (a) Calculate the speed of the earth. (b) Calculate the sun’s mass using the Universal law of gravitation.
Thursday, April 21, 2011
Phys 11 Assignment #3
Solve the following problems in an orderly manner. Follow the Problem-Solving strategy included in the first Fact Sheet. (Should have diagram with coordinate system shown)
1. An airport runway is 1,000 m long. An airplane must attain a speed of 66 m/s to take off. (a) If the average speed of the airplane down the runway is 33 m/s, for what length of time is the plane on the runway? (b) What is the acceleration of the plane?
2. A stone that is initially at rest is dropped from the top of a building. It falls for 5.0 s before hitting the ground. How tall is the building?
3. The unofficial record for a single jump by a frog was set by a South African sharp-nosed frog that leaped 5 m when being retrieved for placement in its container. If this frog left the ground at an angle of 40 degrees above the ground, what was its initial speed?
1. An airport runway is 1,000 m long. An airplane must attain a speed of 66 m/s to take off. (a) If the average speed of the airplane down the runway is 33 m/s, for what length of time is the plane on the runway? (b) What is the acceleration of the plane?
2. A stone that is initially at rest is dropped from the top of a building. It falls for 5.0 s before hitting the ground. How tall is the building?
3. The unofficial record for a single jump by a frog was set by a South African sharp-nosed frog that leaped 5 m when being retrieved for placement in its container. If this frog left the ground at an angle of 40 degrees above the ground, what was its initial speed?
Phys 2 DE
Good morning Phys 2 Group I!
Members of group I:
Hafidah Badio
Sitty Arifah Abdul
Rovan Keatzburg Absalon
Riezynn Harvey Isiderio
Your report is about Momentum and Energy. Assign two (2) members as reporters on Monday and two (2) other members on Tuesday.
Be sure to define the following terms:
Momentum
Impulse
Impulse-Momentum Theorem
Work
Energy
Mechanical Energy
Gravitational Potential Energy
Kinetic Energy
Also include some numerical examples.
:)
Members of group I:
Hafidah Badio
Sitty Arifah Abdul
Rovan Keatzburg Absalon
Riezynn Harvey Isiderio
Your report is about Momentum and Energy. Assign two (2) members as reporters on Monday and two (2) other members on Tuesday.
Be sure to define the following terms:
Momentum
Impulse
Impulse-Momentum Theorem
Work
Energy
Mechanical Energy
Gravitational Potential Energy
Kinetic Energy
Also include some numerical examples.
:)
Thursday, April 14, 2011
Lost and Found Calculator
Lost and Found Calculator.
It was found on March 12, 2011.
The owner might have been enrolled in Phys 21.1 section mn or op
To claim, feel free to visit our office, Room 228, Physics Department.
It was found on March 12, 2011.
The owner might have been enrolled in Phys 21.1 section mn or op
To claim, feel free to visit our office, Room 228, Physics Department.
Time in Manila, Philippines 
