Lesson 2: Machines & Work

Multiple Choice

If no displacement occurs, how much work is done on an object even if a large force is applied?

• Maximum work

• Infinite work

• Zero work

• Negative work

Multiple Choice

Which of the following correctly defines power?

• The total energy stored in a system

• The rate at which work is done

• The force applied over a distance

• The product of mass and acceleration

Multiple Choice

A ___________ is a device that changes the force or increases the motion from work.

• Work

• Job

• Machine

• Calculator

Multiple Choice

Machines can be made more efficient by ____________.

• Increasing input

• Decreasing energy

• Increasing friction

• Reducing friction

Multiple Choice

What is effort (input) force?

• the force one exerts on a machine

• the force which an effort force must overcome in order to do work on an object via a simple machine.

• the force the machine exerts on a object

• the output work times the input distance

Multiple Choice

The amount by which a machine multiplies input force is known as the 

• work.
• power.
• output force.
• mechanical advantage.

Multiple Choice

Efficiency is a measure of

• how much work is done per second

• how much work is output versus to how much work is input

• how much power is used per second

• how much power is output versus how much power is input

Multiple Choice

What is the efficiency of a car that has enough fuel to drive 600 miles, but only actually drives 150 miles?

• 25%

• 4%

• 400

• .25