Download Name Newton`s Laws, Weight, Friction Practice Test 1. Use the

Name _______________________________
Newton’s Laws, Weight, Friction Practice Test
1. Use the following VELOCITY-time graph to answer the questions below.
a. Show all work for finding the acceleration acting on a 100 kg bicycle/rider from 15 to 40 seconds.
b. Show all work for finding the net force acting on the 100 kg bicycle/rider from 15 to 40 seconds.
c. Is the rider moving between 10 and 15 seconds? Is there any net force acting on the rider between 10 and 15
seconds? Are there any forces acting on the rider between 10 and 15 seconds? Explain how your answers can all be
true in terms of Newton’s first and second Laws.
2. A 100 kg man throws a 0.50 kg baseball at 39 m/s East. Assume that the baseball starts at restand the throw takes
0.90 seconds.
a. Show all work for finding the acceleration of the baseball. Remember direction.
b. Show all work for finding the force acting on the baseball. Remember direction.
c. Does the baseball exert any force on the man? If so, how much and in what direction. Explain in terms of Newton’s
third law.
c. Show all work for finding the acceleration of the man assuming there is not friction between the man and the ground.
Remember direction.
d. Are the acceleration of the man and the ball the same? Is that okay according to Newton’s third Law?
e. In reality there is some friction between the man and the ground so that the man does not accelerate. What would
the friction force be in this case? Remember direction.
3. A. Draw a diagram of a 15 kg box being accelerated at a constant 1.34 m/s/s horizontally across a rough floor by an
applied force of 75 N. Include ALL forces acting on the box. All forces should be labeled with a correct name and with
the correct magnitude of the force (with a number of Newtons.
B. Show all work for finding the net force in the vertical direction.
C. Show all work for finding the net force in the horizontal direction.
4. A truck hits a bug with 2.5 N of force to the east. What is the force on the truck? Do these two forces cancel? If so,
why does the bug change its speed? If not, why doesn’t the truck accelerate away from the bug?
5. A 17 kg object is accelerated at -2.3 m/s/s. What net force acted on the object? Is it possible that more than one
force acted on the object? Explain.
6. 13 N of force east and 6.2 N of force west act on a 3.4 kg object. What is the object’s acceleration?
7. What is the mass of a 476 N weighed here on Earth?
8. What is the weight of a 23 kg object here on Earth?
9. a. An object with a weight of 150 N here on Earth is taken to the moon and weighed. On the moon it is found to
weigh 23 N. What is the acceleration of gravity on the moon? What would the object’s mass be on Earth? What would
the object’s mass be on the moon?
b. What Normal force would act on that object if it were rolling along at a constant speed on flat solid ground on the
moon?
c. What net force would act on that object if it were rolling along at a constant speed on flat solid ground on the moon?
d. What acceleration would act on that object if it were rolling along at a constant speed on flat solid ground on the
moon?
e. What normal force would act on that object if it were dropped off a cliff on the moon?
f. What net force would act on that object if it were dropped off a cliff on the moon? (ignore air resistance)
g. What acceleration would act on that object if it were dropped off a cliff on the moon? (ignore air resistance)
h. As it falls it actually experiences some friction with the air (air resistance). If it experiences 7 N of friction, what
direction would the air resistance act?
i. What net force would act on that object if it were dropped off a cliff on the moon if we included the air resistance?
j. What acceleration does it experience when dropped if we include the air resistance?
10. a. If a 35 Newton backpack is sitting on the ground and has a coefficient of .5 with the ground, and I push
horizontally on the backpack with a force of 15 Newtons, what is the acceleration on the backpack? What is the normal
force while I am pushing the backpack?
b. If I push with 25 Newton of force, what is the acceleration of the back pack?
11. A 700.0 N man stands on a scale in an elevator.
a. What is the man’s mass?
What would the scale read:
b. When it accelerates upward at 2.1 m/s/s?
c. When it goes upward at a constant 4.2 m/s?
d. When it is going upward but slows down to a stop at 1.8 m/s/s?
e. When it accelerates downward at 1.95 m/s/s?
f. when the elevator is at rest?
g. when it is going downward but slows at 1.8 m/s/s
12. a. A 3.2 kg book is pushed across a desk with an applied force of 7 N which causes it to decelerate at -1.4 m/s/s.
Draw a Free body diagram showing, naming and calculating the magnitude of all of the forces acting on the book.
b. Find the coefficient of friction between the book and the desk.
c. Repeat 12a for the case where a 1 kg mass is laid on top of the first. The applied force is the same.
d. What is the acceleration of the book with the mass on it?
13. A 9kg sled with a 25 N boy is pulled across the snow at a constant acceleration of 1.3 m/s/s with a tension force of
23 N. What is the coefficient of friction between the sled and the boy?
13. What acceleration would the sled experience if the boy fell off the sled, but the tension force remained the same.
14. While accelerating a 1400 kg car tire has a coefficient of friction of .26 with the wet asphalt road.
a. What is the friction force
b. What is the greatest acceleration the car could have?
c. What would happen if the car tried to accelerate faster than the rate you found in part b.
15. Floyd Mayweather is a world champion boxer who can easily punch another person with 5000N of force. If I drop a
piece of paper in front of Floyd and ask him to hit it as hard as he can he can only generate about 2 N of force. Why
can’t he hit the paper harder?