PSc Review Day 3

In which of the following is no work done?

• Climbing stairs

• Lifting a book

• Pushing a shopping cart

• Work is being done in all choices

The efficiency of a machine is always less than 100% because

• A machine cannot have an IMA greater than 1

• Some work input is lost to friction

• The work input is too small

• The work output is too great

Conduction is the transfer of heat energy by

• density differences

• molecular contact

• electromagnetic waves

• movement through a vacuum

A bicyclist sitting at the top of a hill begins to coast without pedaling. The bicycle speeds up as it descends to the bottom of the hill and then slows down as it continues up a second hill, where it stops. Which of these sequences BEST describe the energy change of the bicycle from the top of the hill until it stops?

• Potential – Kinetic – Kinetic

• Kinetic – Potential – Potential

• Kinetic – Potential – Kinetic

• Potential – Kinetic – Potential

If 10 milligrams of iodine-131 is given to a patient, how much is left after 24 days? The half-life of iodine-131 is 8 days.

• 10 mg

• 5 mg

• 2.5 mg

• 1.25 mg

Order the types of radiation from least penetrating to most penetrating.

• gamma < beta < alpha

• gamma < alpha < beta

• alpha < beta < gamma

• beta < gamma < alpha

A girl lifts a 100 N load a height of 2 m in a time of 0.5 s. What power does she produce?

• 400 W

• 50 W

• 20 W

• 1 W

The weight lifter lifted a mass of 100 kg barbell over her head in 5.21 seconds. Approximately how much power did she do in raising the barbell?

• 384 W
• 15.21 W

• 521 W

• 100 W

An explosion of gas from a Hawaiian volcano blows a rock into the sky. The rock has 2000 J of kinetic energy. What was its mass if the rock had a velocity of 20 m/s?

• a. 200 kg

• b. 10 kg

• c. 20,000 kg

• d. 250 kg

Which of the following has the greatest amount of gravitational potential energy?

• a. A 20 kg projector suspended 10 m in the air

• b. A 5 kg basketball suspended 10 m in the air

• c. A 100 kg wrecking ball suspended 10 m in the air

• d. They all have the same GPE because they are all 10 m in the air