Work and Power

How is work defined in physics?

• The power transferred when a force is applied to move an object over a distance.

• The energy transferred when a force is applied to move an object over a distance.

• The energy transferred when a force is applied to move an object over a given time.

• The power transferred when a force is applied to move an object over a given time.

The amount of work done depends on what two quantities?

• Force and time

• Power and time

• Force and distance

• Power and distance

Positive work is done when the force is applied ___________

• in the same direction as displacement.

• perpendicular to the displacement.

• over a given amount of time.

• in the opposite direction of the displacement.

Negative work is done when the force is applied ___________

• in the same direction as displacement.

• perpendicular to the displacement.

• over a given amount of time.

• in the opposite direction of the displacement.

What is the relationship between work and distance?

• Inversely proportional

• Parabolic

• Directly proportional

• There is no relationship

What is the equation for work?

• W = F x d

• W = F/d

• W = d/F

• W = P/t

If you push against a car, but the car doesn't move, are you doing any work?

Explain.

• Yes - Anytime a Force is applied over a given amount of time work is done.

• Yes - Anytime a Force is done and Power is developed work is don't.

• No - if the car doesn't move, then no work is done.

• No - work can only be achieved through machines?

What is the SI unit for work?

• Newtons (N)

• Joules (J)

• Watts (W)

• Horsepower (Hp)

A box is pushed with a 50 Newton force for a distance of 2 meters. The process takes 5 seconds. How much work was done on the object?

• 100 J

• 10 W

• 20 W

• 250 J

• 125 W

A box is pushed with a 50 Newton force for a distance of 2 meters. The process takes 5 seconds. What is the power rating of the work done to the object?

• 100 J

• 10 W

• 20 W

• 250 J

• 125 W