South Pasadena • Physics Name
4 · Forces Period Date
PRACTICE TEST
DIRECTIONS· Please use a pencil to complete this test. A scientific calculator is allowed. No other resources are permitted.
· Please show all work neatly for free response computational problems. Include all the appropriate units and show how they work out. Any answer without adequate work will not be given full credit. Answers should be recorded with the two significant figures, the correct direction (+ or –, if applicable), and units.
· Work does not need to be shown for multiple choice questions.
· Assume that “up” or “right” is the positive direction, and “down” or “left” is the negative direction. Assume that air resistance is negligible, unless otherwise specified. Use g = 9.8 m/s2, unless otherwise specified.
FORMULAS
d = vt
d = vot + ½ at2 / d = t / v = vo + at
v2 = vo2 + 2ad
v =
q = tan–1 / vx = v cos q
vy = v sin q / dx = vxt
dy = voyt + ½ at2
vy = voy + at
vy2 = voy2 + 2ady
F = ma / W = mg / P =
SECTION 1: MULTIPLE CHOICE (2 points each)
1. Which of the following quantities has/have the unit of newtons?
(A) inertia
(B) mass
(C) pressure
(D) weight
(E) acceleration
2. Which of the following statements about inertia is NOT correct?
(A) Inertia is an object’s resistance to changing its motion.
(B) An object’s weight is a measure of inertia.
(C) The greater an object’s mass, the more inertia it has.
(D) If an object is moving, it will keep traveling in that direction at the same speed because of its inertia.
(E) It is easier to accelerate an object with lesser inertia than one with greater inertia.
3. A 5-kg ball is moving at a constant speed of 3.0 m/s. It has the same net force as:
(A) another 5-kg ball at rest.
(B) another 5-kg ball when it is dropped from a 3.0 m platform.
(C) another 5-kg ball with an acceleration of 1.5 m/s2 after 2 seconds.
(D) a 10-kg ball moving with an acceleration of 1.5 m/s2.
(E) a 10-kg ball moving with an acceleration of 6.0 m/s2.
4. An egg is dropped from a height of 100 m. Another egg with the same mass is thrown down from the same height. Which of the following is NOT true?
(A) The two eggs have the same inertia.
(B) The net force on the eggs when they hit the ground is the same.
(C) The two eggs have the same weight.
(D) The acceleration on the eggs when they hit the ground is the same.
(E) All of the above are true.
5. A 20-N force is applied to each of the following balls. Which object will experience the greatest acceleration?
(A) tennis ball m = 0.060 kg
(B) baseball m = 0.140 kg
(C) billiard ball m = 0.160 kg
(D) volleyball m = 0.250 kg
(E) softball m = 0.200 kg
6. A particular truck weighs 5880 N on the moon, while a 600-kg car weighs 5880 N on the earth. If the acceleration due to gravity on earth is 6.125 times that on the moon, what is the mass of the truck?
(A) 60 kg
(B) 98 kg
(C) 600 kg
(D) 960 kg
(E) 3675 kg
7. A wad of paper is pushed by a blowing fan exerting a force of 0.12 N. If the paper accelerates at 3.0 m/s2, what is the mass of the wad?
(A) 0.04 kg
(B) 0.36 kg
(C) 1.2 kg
(D) 25 kg
(E) 29 kg
8. A box is suspended by two ropes that make 45 degrees with the box. How many force vectors would be drawn in the free body diagram?
(A) 1
(B) 2
(C) 3
(D) 4
(E) 5
9. A 5.0-kg book is pulled by a rope horizontally with a tension of 30 N. The force of friction is 10.0 N. What is the net acceleration experienced by the system?
(A) 0 m/s2
(B) 2.0 m/s2
(C) 4.0 m/s2
(D) 6.0 m/s2
(E) 9.8 m/s2
10. A 5-kg pumpkin is thrown down a cliff and accelerates until it reaches its terminal velocity. What is the net force on the pumpkin at this point?
(A) 0 N
(B) 5 N
(C) 9.8 N
(D) 25 N
(E) 49 N
11. A 10-kg crate is pushed across the floor at the constant speed of 2.0 m/s. If the force of friction experienced by the crate is 5 N, with what force is the crate pushed?
(A) 0 N
(B) 5 N
(C) 10 N
(D) 20 N
(E) 98 N
12. A particular rope can support a maximum tension of 70 N. What is the minimum number of ropes (hung vertically) required to suspend a large box with a mass of 50 kg?
(A) 1
(B) 2
(C) 4
(D) 7
(E) 12
13. A hammer pounds vertically on a nail. State the reaction force for the following action: The hammer is pulled down by the earth, which is the force of gravity.
(A) The earth is pulled up by the hammer.
(B) The hammer pushes the nail down.
(C) The nail pushes the hammer up.
(D) The nail is pulled down by the earth.
(E) The earth is pulled up by the nail.
14. When a 200 Pa pressure is applied to an object with a rectangular area of 1.2 m by 1.5 m, the object accelerated at 6.0 m/s2. What is the mass of the object?
(A) 0.05 kg
(B) 33 kg
(C) 60 kg
(D) 111 kg
(E) 670 kg
15. Which of the following expresses a pascal in fundamental SI units?
(A) kg · m · s–2
(B) kg · m–1 · s–2
(C) kg · m · s2
(D) kg · m–2 · s–1
(E) kg · m–2 · s–2
SECTION 2: FREE RESPONSE
16. The acceleration due to gravity on the sun is 28 times that on earth. If a person has a mass of 60 kg, find the person’s weight on the sun.
17. A 1.2 kg hammer hits a 0.050 kg nail. If the acceleration of the nail is 2.5 m/s2, what is the acceleration of the hammer as it hits the nail? I E S A
18. Draw the free diagram for the following ball rolling down a ramp at a constant speed.
19. A 75-kg block is pushed with a force of 150 N across the floor with a friction of 60 N.
(a) Draw the free body diagram for this motion.
(b) What is the acceleration with which this block moves? I E S A
20. In the setup shown, object A has a mass of 4 kg and object B has a mass of 8 kg.
(a) Draw the free body diagram for this system.
(b) What is the acceleration with which this system moves? I E S A
21. A car is traveling along the road. Draw a diagram indicating all the relevant action and reaction forces.
22. A 5-kg mass accelerates at 3.0 m/s2 when a 300 Pa pressure is applied. What is the surface area of this mass?
I E S A