AP Physics - Gull Lake Girls' Basketball Google Calendar



AP Physics A

UNIT 4 PRACTICE PROBLEMS

Multiple Choice: Choose the best answer to each question below.

1. An astronaut whose mass is 50 kg on the surface of Earth discovers that his mass is also 50 kg on the surface of planet X. What is the acceleration due to gravity on the surface of planet X?

a) 50 m/s2 b) 10 m/s2 c) 1 m/s2 d) 0 m/s2 e) It cannot be determined from this information.

2. The diagram to the right shows a ball tied to a mass which is being whirled

in a vertical circle at a constant speed. At which of the four labeled points on

the circle would the tension in the string be greatest?

a) A b) B c) C d) D e) The tension would be the same at all four points.

3. A wheel of radius R and negligible mass is mounted on a horizontal frictionless

axle so that the wheel is in a vertical plane. Three small objects having masses m,

M, and 2M are mounted on the rim of the wheel as shown to the right. If the system

is in static equilibrium, what is the value of m in terms of M?

a) M/2 b) M c) 3M/2 d) 2M e) 5M/2

4. The nonuniform bar shown below is 5 meters long. It is denser near one end than near the other end. It has a fixed pivot at 2.3 m from the heavy end (H). If the weight of the bar is 73.3 N and a 20 N weight at 0.5 m from the light end of the bar (L) will establish rotational equilibrium, what is the location of the bar’s center of mass?

a) 0.13 m left of the pivot b) 0.6 m from the heavy end c) 1.7 m from the heavy end d) 2.5 m from the light end e) 2.9 m from the heavy end

5. As a merry-go-round rotates with a constant angular speed. As a rider moves from the rim of the merry-go-round toward the center, what happens to the magnitude of the centripetal force that must be exerted on him?

a) It increases. b) It decreases. c) It remains the same. d) It could increase or decrease depending on the direction of rotation.

6. A lead bullet is placed in a pool of mercury. What fractional part of the volume of the bullet is submerged?

a) 0.455 b) 0.622 c) 0.714 d) 0.831 e) 0.930

7. A horizontal pipe narrows from a radius of 0.25 m to 0.10 m. If the speed of the water in the pipe is 1.00 m/s in the larger radius pipe, what is the speed of the water in the smaller radius pipe?

a) 2.5 m/s b) 3.75 m/s c) 4.5 m/s d) 5.13 m/s e) 6.25 m/s

Free Response: Answer each question or solve each problem below. Explain or show any work necessary.

1. A pump, submerged at the bottom of a well that is 35 m deep, is used to pump water uphill to a house that is 50 m above the top of the well, as shown in the diagram. The density of water is 1,000 kg/m3. All pressures are gauge pressures. Neglect the effects of friction, turbulence and viscosity.

a) Residents of the house use 0.35 m3 of water per day. The day’s pumping is completed in 2 hours during the day.

i. Calculate the minimum work required to pump the water used per day.

ii. Calculate the minimum power rating of the pump.

b) The average pressure the pump actually produces is 9.20 x 105 N/m2. Within the well the water flows at 0.50 m/s and the pipe has a diameter of 3.0 cm. At the house the pipe diameter is 1.25 cm.

i. Calculate the flow velocity when a faucet in the house is open.

ii. Explain how you would calculate the minimum pressure at the faucet.

2. A nonuniform bar 4 m long having a weight of 70 N is shown below. The bar is on a fixed pivot at its center of mass which is 1 m from the heavy end. A 300 N weight is placed 0.4 m left of the center of mass and a 100 N weight is placed 1.0 m right of the center of mass.

a) List the clockwise and counterclockwise torque values individually.

b) What is the magnitude and the direction of the net torque?

c) Where must a 200 N weight be placed to establish rotational equilibrium?

d) If a 400 N weight is placed in this same location, what is the net torque (magnitude and direction)?

3. A 200 kg crate and 500 kg boulder are placed 0.4 m apart.

a) Find the net gravitational force exerted by these objects on a 50 kg backpack placed midway between them.

b) At what position between the crate and the boulder could the backpack be placed so that the net gravitational force exerted on the backpack by the crate and boulder would be zero?

-----------------------

B

Pivot

20 N

0.5 m

2.3 m

H

L

A

D

C

[pic]

0.4 m

1.0 m

300 N

100 N

Pivot (CM)

Light end

Heavy end

[pic]

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download