Download Test 3: Version A

Test 2: Study Guide
Know the Following Topics
You can use an index card no larger than 3x5 inch. You can include any equations, notes,
sample problems that you may want to use for the test. The test will cover MATERIAL
COVERED on Ch 4 and Ch 5.
Ch 4.
1. Know the difference between mass and weight
2. Know that weight is a force
3. Inertia (know that mass is how we measure inertia, the more inertia the more mass)
4. Newton’s Laws (1st, 2nd, 3rd)
5. Friction (always opposes the applied force)
6. Free Fall
7. Equilibrium
8. Normal Force,
Ch 5.
1. Work (Work KE Theorem)
2. Energy (KE, PEg, PEe,)
3. Conservation of Mechanical Energy
SAMPLE PROBLEMS
Difference Between mass and weight
1. A student weighs 588 N. What is her mass?
a. 25 kg
b. 59 kg
c. 68 kg
d. 71 kg
Weight is a force
2. A student holds a book at rest in an outstretched hand. The force exerted on the book by the
student is equal to the book’s
a. mass
b. weight
c. volume
d. density
3. The weight of 5 kg of mass is:
a) 7.8 N
b) 49 N
c) 4.45 N
d) 0 N
Inertia
4. Which of the following objects has the larger amount of inertia: 2.5 kg of feathers, 1.0 kg of
steel, 1.5 kg of wood, 2.0 kg of glass
a) 2.5 kg of feathers
b) 1.0 kg of steel
c) 1.5 kg of wood d) 2.0 kg of glass
5. Which of the following is true about mass?
a) depends on gravity
b) depends on altitude c) depends on location
d) none of these
Newton’s Laws
6. The net force on the propeller of a 3.2 kg model airplane is 7.0 N forward. What is the
acceleration of the airplane?
A. 2.2 m/s2 forward B. 1.4 m/s2 north
C. 14 m/s2 west
D. 4.50 m/s2 eastward
7. A soccer ball kicked with a force of 13.5 N accelerates at 6.5 m/s2 to the right. What is the
mass of the ball?
A. 7.3 kg
B. 1.0 kg
C. 2.1 kg
D. 9.1 kg
8. For problem 7, what is the force experienced by a player’s foot the moment she kicks the
ball?
A. 15 N
B. 10 N
C. 13.5 N
D. It will depend on the
Mass of the player
9. How much force or thrust must a 18000 kg jet plane develop to achieve an acceleration of
2.5 m/s2?
a) 9.2x104 N
b) 3.0x104 N
c) 4.5x104 N
d) 1.5x104 N
10. The forces acting on a sailboat are 300 N north and 225 west. If the boat and its contents
have a mass of 300 kg, what is the magnitude of the boat’s acceleration?
a. 2.5 m/s2
a. 1.8 m/s2
a. 1.25 m/s2
a. 3.2 m/s2
11. For problem 10, what is the direction of the acceleration?
a. 37 W of N
b. 53 N of W
c. 225 N of W
d. 25 W of N
Normal Force
12. What is a general characteristic of the normal force?
a) always perpendicular to the surface of an object
c) always oppose the motion of the object.
b) always = g
d) static friction is always less than kinetic friction
Friction
Use the passage below to answer questions 13- 15.
A tractor pulls a loaded wagon on a level road with a constant horizontal force of 440 N. The
wagon experiences an opposing force of friction Fk= 140 N. The total mass of the wagon and its
contents is 275 kg.
13. What is the net force experienced by the wagon?
a. 300 N
b. 580 N
c. 440 N
d. 715 N
14. What is the magnitude of the wagon’s acceleration?
a. 2.5 m/s2
b. 3.8 m/s2
c. 1.1 m/s2
d. 0 m/s2
15. If the wagon started from rest and the acceleration is constant, how far will it travel in 4.00
s?
a. 3.9 m
b. 2.1 m
c. 9.11 m
d. 8.7 m
16. What is a general characteristic of all types of friction?
a) always perpendicular to the plane of an object
c) always = g
b) always oppose the motion of the object.
d) static friction is always less than kinetic friction
Use the passage below to answer questions 17 and 18.
The coefficient of static friction between a 40 kg crate and the floor is 0.65.
17. What is the magnitude of the minimum horizontal force a worker must pull to get the crate
moving?
a. 300 N
b. 255 N
c. 120 N
d. 97 N
18. If the worker maintains the force, the crate starts to move and the coefficient of kinetic
friction between the surfaces is 0.500, what is the magnitude of the acceleration of the crate?
Hint! The crate is NOT in equilibrium!
a. 5.21 m/s2
b. 2.11 m/s2
c. 0.97 m/s2
d. 1.47 m/s2
Equilibrium
19. A 20 newton force and a 15 newton force are acting from a single point in opposite
directions. What additional force must be added to produce equilibrium?
a. 5 N acting in the same direction as the 15 N force
b. 5 N acting in the same direction as the 20 N force
c.10 N acting in the same direction as the 20 N force.
d. 35 N acting in the same direction as the 15 N force.
20. The graph below shows the velocity of a car that is moving in a straight line.
During which of the following intervals are forces on the car balanced?
a. q to r
b. r to s
c. s to t
d. t to u
21. If a car is accelerating downhill under a net force of 3674 N, what additional force would
cause the car to have a constant velocity? Hint! This is an equilibrium problem!
A. -3674 N
B. 0 N
C. -8990 N
D. 3674 N
W, KE, PE, ME
22. On a frozen pond, a person kicks a 10.0 kg sled at rest, giving it a final speed of 2.2 m/s.
What was the work done on the sled?
A. 37 J
B. 24 J
C. 91 J
D. 382 J
Use the following passage to answer questions 23-29
Starting from rest, a 20 kg child zooms down a frictionless slide from an initial height of
5.00 m.
23. What is her potential energy at the top of the slide?
A. 1000 J
B. 0 J
C. 572 J
D. 132 J
24. What is her potential energy at the bottom of the slide?
A. 1000 J
B. 0 J
C. 572 J
D. 132 J
25. For #13, where did that energy go?
A. it was converted to potential energy
B. it was converted into elastic energy
C. it was converted into work
D. it was converted into kinetic energy
26. What is the kinetic energy of the child at the top?
A. 1000 J
B. 0 J
C. 572 J
D. 132 J
27. What is the kinetic energy of the child at the bottom?
A. 1000 J
B. 0 J
C. 572 J
D. 132 J
28. Calculate the speed of the child at she reaches the bottom of the slide?
A. 9 m/s
B. 3 m/s
C. 5.72 m/s
D. 10 m/s
29. This exercise best exemplifies which physical principle?
A. conservation of momentum
B. conservation of Mass
C. conservation of mechanical energy D. conservation of quantum numbers
Use the graph below to answer questions 30–32. The graph shows the energy of a 75 g
yo-yo at different times as the yo-yo moves up and down on its string.
30. Approximately, by what amount does the mechanical energy of the yo-yo change after 7.5
s?
A. -80 mJ
B. 0 mJ
C. –175 mJ
D. 250 mJ
31. What is the speed of the yo-yo after 4.5 s?
A. 3.1 m/s
B. 2.3 m/s
C. 3.6 m/s
D. 1.6 m/s
32. What is the height of the yo-yo at 7.0 s?
A. 27 cm
B. 54 cm
C. 75 cm
D. 82 cm
33. Three objects move with a velocity of 1.0 m/s. What is the total kinetic energy of the system
a. 1 J
b. 5 J
c. 2 J
d. 10 J
34. A 50-kilogram firefighter is on a ladder 10 meters above the ground. When the firefighter
descends to 5 meters above the ground, the firefighter’s gravitational potential energy will
decrease by
a. 0.194 J
b. 490 J
c. 5.10 J
d. 2450 J