# Modern Physics Multiple Choice Questions

1. Use the work-energy theorem to find the force required to accelerate

an electron (m = 9.11 x 10-31 kg) from rest to a speed of 1.50 x 107 m/s

in a distance of 0.0125 m.

a. 8.20 x 10-15 N

b. 5.47 x 10-22 N

c. 8.20 x 10-17 N

d. 1.64 x 10-14 N

e. 3.56 x 10-19 N

2. Use the work-energy theorem to find the force required to accelerate

an electron (m = 9.11 x 10-31 kg) from rest to a speed of 1.50 x 107 m/s

in a distance of 0.0125 m.

a. 8.20 x 10-15 N

b. 5.47 x 10-22 N

c. 8.20 x 10-17 N

d. 1.64 x 10-14 N

e. 3.56 x 10-19 N

3. A ceiling fan has five blades, each with a mass of 0.34 kg and length of

0.66 m. The fan is operating in its "low" setting at which the angular

speed is 9.4 rad/s. If the blades can be approximated as uniform thin

rods that rotate about one end, what is the total rotational kinetic

energy of the five blades?

a. 35 J

b. 29 J

c. 23 J

d. 17 J

e. 11 J

4. The spring constant for the spring in a special cannon is 1800 N/m. In

cocking the cannon, the spring is compressed 0.55m. What is the initial

speed of a 7.0-kg cannonball at rest on the free end of the spring when

it is released?

a. 77 m/s

b. 140 m/s

c. 12 m/s

d. 8.8 m/s

e. 16 m/s

5. A cylinder with a radius of 0.120 m is placed between the plates of a

hydraulic press as illustrated in the drawing. A 4.45 x 105 -N force is

applied to the cylinder. What is the pressure on the end of the cylinder

due to the applied force?

a. 9.84 x 106 Pa

b. 3.13 x 105 Pa

c. 6.18 x 106 Pa

d. 5.34 x 104 Pa

e. 3.71 x 106 Pa

6. A child wants to pump up a bicycle tire so that its pressure is 2.5 x 105

Pa above that of atmospheric pressure. If the child uses a pump with a

circular piston 0.035 m in diameter, what force must the child exert?

a. 120 N

b. 240 N

c. 340 N

d. 930 N

e. 1300 N

7. The two dams are identical with the exception that the water reservoir

behind dam A extends twice the horizontal distance behind it as that of

dam B. Which one of the following statements regarding these dams is

correct?

a. The force exerted by the water on dam A is greater than that on

dam B.

b. The force exerted by the water on dam B is greater than that on

dam A.

c. Dam A is more likely to collapse than dam B if the water level

rises.

d. Dam B is more likely to collapse than dam A if the water level

rises.

e. The horizontal distance of the water behind the two dams does

not determine the force on them.

8. The density of ice is 0.92 g/cm3, and the density of seawater is 1.03

g/cm3. A large iceberg floats in Artic waters. What fraction of the

volume of the iceberg is exposed?

a. 0.080%

b. 11%

c. 89%

d. 92%

e. 99%

9. Alyssa went to her outside faucet to fill a 0.032-m3 bucket with water

to wash her car. Water exits with a speed of 0.64 m/s. The radius of the

faucet is 0.0075 m. How long does it take to fill the bucket completely?

a. 9.0 s

b. 17 s

c. 190 s

d. 280 s

e. 890 s

10. The coefficient of linear expansion of a certain solid is 9 x 10-6/C°.

Assuming this solid behaves like most solids, what is its coefficient of

volume expansion?

a. 9.1 x 10-6/C°

b. 27 x 10-36/C°

c. 27 x 10-6/C°

d. 729 x 10-6/C°

e. 729 x 10-36/C°

11. A 2.00-kg metal object requires 5.02 x 103 J of heat to raise its

temperature from 20.0°C to 40.0°C. What is the specific heat capacity

of the metal?

a. 63.0 J/(kg?C°)

b. 126 J/(kg?C°)

c. 251 J/(kg?C°)

d. 502 J/(kg?C°)

e. 1.00 x 103 J/(kg?C°)

12. A 0.20-kg lead shot is heated to 90°C and dropped into an ideal

calorimeter containing 0.50 kg of water initially at 20.0°C. What is the

final equilibrium temperance of the lead shot? The specific heat

capacity of lead is 128 J/(kg?C°), and the specific heat of water is 4186

J/(kg?C°).

a. 4.8°C

b. 20.8°C

c. 22.4°C

d. 27.8°C

e. 42.1°C

13 . Heat is added to a sample of water in an insulated container. Which

one of the following statements is necessarily true?

a. The temperature of the water will rise.

b. The volume of the water must decrease.

c. The mass of the system must decrease.

d. Under certain conditions, the temperature of the water can

decrease.

e. The type of change that will occur depends on the original

temperature of the water.