Work and Power - Rehearse

Front

What is the definition of work in physics?

Back

Work is done when a force causes an object to move in the direction of the force. It is calculated as the product of force and distance (W = F x d).

Front

True or False: Work is done when a weightlifter holds a barbell still above his head.

Back

False. Work is only done when there is movement in the direction of the force applied.

Front

How do you calculate the force used if 150 Joules of work is done to move a box 10 meters?

Back

Force (F) can be calculated using the formula W = F x d. Rearranging gives F = W/d = 150 J / 10 m = 15 N.

Front

Which produces more power: lifting a mass of 10 kg 10 meters in 10 seconds or in 5 seconds?

Back

Lifting the mass in 5 seconds produces more power because power is the rate of doing work, and less time means more power.

Front

What is the formula for calculating work?

Back

The formula for work is W = F x d, where W is work, F is force, and d is distance.

Front

If a weightlifter lifts two 300 N weights 1.5 meters, how much work is done?

Back

Work done = Force x Distance = (2 x 300 N) x 1.5 m = 900 J.

Front

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

Back

The unit of work is the Joule (J).

Front

Define power in the context of physics.

Back

Power is the rate at which work is done or energy is transferred, calculated as Power = Work / Time.

Front

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

Back

The unit of power is the Watt (W), where 1 Watt = 1 Joule/second.

Front

If a machine does 2000 J of work in 10 seconds, what is its power output?

Back

Power = Work / Time = 2000 J / 10 s = 200 W.