Physics Practice Exam

Physics Practice Exam

February 14th

1. The components of vector A and vector B are given as follows:

Ax = -2.9 Bx = 3.4

Ay = 7.0 By = -4.2

The magnitude of the vector difference A – B is:

(A) 12.85 (B) 6.90 (C) 2.85 (D) 9.40 (E) 13.40

2. If the vector D = -4i +5 j +10k, what is the unit vector D ?

(A) D = +0.04i + 0.05 j + 0.10k

(B) D = −0.33i + 0.42 j + 0.84k

(D) D = −0.04i + 0.05 j − 0.10k

(E)D = −0.28i + 0.35 j − 0.70k

3. Sally weighs 1000N. She is standing in an elevator that is accelerating downwards at a

rate of 4.9m/s². What is the magnitude of the net force acting on Sally?

(A) 0N (B) 500N (C) 1000N (D) 1500N (E) 2000N

4. A 180g block is propelled from rest along a frictionless track by a spring that is

compressed by 20cm from its relaxed length. Further along the track there is a frictionless

upwards incline sloped at 30º above the horizontal. The block slides up the ramp until it

is at a height of 1m above the ground level and then comes momentarily to a stop. What

is the force constant, k, of the spring?

(A) 44.1J (B) 44.1N/m (C) 88.2 J (D) 88.2 N/m (E) 176 N/m

5. If John walks 3km north at 2.5km/hr, then runs another 2km east at 15.0km/hr, then he heads south for 20 minutes at a rate of 9km/hr, and then turns west for 30 minutes at 2km/hr. What is the magnitude of his average velocity during the 2km trip?

(A)28.5 km/hr (B)14.3 km/hr (C)2.17 km/hr(D)0.46 km/hr (E) 0 km/hr

6. Suppose that a particle moving along the x-axis has velocity as a function of time

described by “v(t) = at³ + bt^4” where a=1m/s^4 and b=2m/s^5. What is the acceleration of the particle at t=3s?

(A) a=0 m/s² (B) a=27 m/s² (C) a=189 m/s² (D) a= 216 m/s² (E) a=243 m/s²

7. City A is 600 km directly west of city B. A plane has an air speed of 210 km/hr. If

there is wind blowing north at 150 km/hr, what is the time it takes to fly from city A to

city B? Assume that the air traffic controllers have routed the plane to fly directly over

the interstate which runs in a straight line from A to B.

(A)2.50hr (B) 2.86hr (C)4.00hr (D)4.08hr (E)5.06hr

8. A 4-kg book is kept fixed against a vertical wall by a hand that applies a 200-N force perpendicular to the surface of the book. The coefficient of static friction between the book and the wall is μS = 0.3. What is the magnitude of the friction force?

(A) 12N (B) 20N (C) 39N (D) 59N (E)200N

9. Pete applies a horizontal force F=15N on the system depicted below, made of two boxes A and B placed on a frictionless horizontal floor. The masses of the boxes are mA = 30 kg and mB = 20 kg. What is the magnitude of the acceleration of box B?

(A) 0, you cannot move an object whose weight is 500 N with a 15-N force.

(B) 0.3 m/s2 (C) 0.5 m/s2 (D) 1.0 m/s2 (E)1.2 m/s2

10. In Problem 9, the magnitude of the net force on box A is ______than the magnitude of the net force on box B.

(A) Four times (B)Twice (C)One and a Half (D) The Same As (E)One fourth

11. There is a system made of 3 blocks of mass m on a flat surface connected by a string to a pulley with 2 blocks of mass 2m and m hanging freely. The friction between the blocks and the table is negligible. What is the acceleration of the system? (Where g is the acceleration of gravity.)

(A) 2g (B) 3g/2 (C) g (D) g/2 (E) g/4

12. A person drives a car over the top of a hill, the cross section of which can be

approximated by a circle of radius 1024m. What is the greatest speed at

which he can drive without the car leaving the road at the top of the hill?

(A) 25 m/s (B) 50 m/s (C) 100 m/s (D) 150 m/s (E) 200 m/s

13. Four blocks of masses m1=1kg, m2=2kg, m3=3kg, m4=4kg are on a frictionless

horizontal surface. The blocks are connected by ideal massless strings. A force FL=20N is applied to the left block and is directed to the left. Another force FR=60N is applied to the right block, and is directed to the right. What is the magnitude of the tension T in the string between m3 and m4.

(A) T=16N (B)T=20N (C)T=44N (D)T=52N (E)T=60N

14. A small stone is placed at the rim (R=19.0cm) of a level pottery wheel of radius R = 19.0 cm. The wheel is initially at rest and begins moving with a constant angular acceleration of 0.200 rad/s2. When the system reaches 4.00 rad/s, the stone flies off. What is the coefficient of static friction between the wheel and the stone?

(A) 0.18 (B) 0.31 (C) 1.3 (D) 1.6 (E) 1.9

15.In Problem 14, how many revolutions does the wheel do before the stone flies off?

(A) 3.8 (B) 6.4 (C) 9.2 (D) 10.2 (E) 20

16. If I throw a 5 kg brick directly down with v=10m/s from a height of 2 meters above a spring that it lands squarely on, and spring constant 1000 N/m, how far will the spring compress before the brick is shot back up?

(A) 0.834 m (B) 0.443 m (C) 0.326 m (D) 0.707 m (E) 0.200 m

17. After the brick in problem 16 compresses the spring, it will shoot back up. How high above the spring will the block bounce before falling back down?

(A) 3.10 m (B) 4.50 m (C) 5.50 m (D) 7.10 m (E) 9.60 m

18. Robin Hood fires an arrow at velocity v0=45m/s at an angle of θ=30o above the

horizontal from the top of a cliff of height h. The sheriff of Nottingham standing at

distance d from the base of the cliff notices that the arrow impacts him with a speed of

92m/s. What is the height h of the cliff? Neglect air resistance.

(A) h=212m (B) h=290m (C) h=330m (D) h=400m (E) h=420m

19. A man exerts a 250-N force to pull and 125-kg crate up an incline with a rope that

makes an angle with the incline of 36 degrees. What is the work done by the man when

he pulls the crate 4.0 m along the incline?

(A) 125 J (B) 225 J (C) 588 J (D) 809 J (E) 1000 J

20. A 100kg block rests on a horizontal frictionless ice surface. Jane pulls the block

north with a force of 100N while Sue pulls the block east with a force of 144N. What is the magnitude of the acceleration of the block?

(A) 0.00 m/s² (B) 0.85 m/s² (C) 1.00 m/s² (D) 1.44 m/s² (E) 1.75 m/s²