Understanding Work and Power

What is the unit of work in the International System of Units (SI)?

• Joule

• Newton

• Watt

• Pascal

If a force of 10 N is applied to push a box 5 meters, how much work is done on the box?

• 2 J

• 15 J

• 50 J

• 500 J

What is power defined as in physics?

• The rate at which energy is transferred

• The rate at which work is done

• The force applied to an object

• Both A and B

A machine does 100 J of work in 5 seconds. What is the power output of the machine?

• 20 W

• 50 W

• 100 W

• 500 W

Which of the following scenarios involves no work being done according to the physical definition of work?

• Pushing against a wall with all your might

• Lifting a book off the floor

• Carrying a bag while walking at a constant speed

• Pulling a wagon up a hill

If the power output of a motor is 1500 watts, how much work does it do in 3 seconds?

• 4500 J

• 500 J

• 1500 J

• 450 J

What is the work done by gravity on a satellite orbiting Earth at a constant height?

• Zero, because there is no displacement

• It depends on the mass of the satellite

• It depends on the speed of the satellite

• It cannot be determined without additional information

If you lift two loads up one story, one twice as heavy as the other, but you take twice as long to lift the heavier load, how do the powers expended compare?

• The power expended on both loads is the same

• The power expended on the heavier load is twice as much

• The power expended on the lighter load is twice as much

• The power expended on the heavier load is four times as much

What happens to the work done when the angle between the force applied and the direction of motion is 90 degrees?

• It increases

• It decreases

• It remains the same

• It becomes zero

A person holds a 20 N weight stationary at arm's length. How much work is the person doing on the weight?

• 0 J

• 20 J

• It depends on how long they hold it

• It depends on the strength of the person