Ch 7 Simple Machines

Positive work is done when force is applied to an object in which of the following directions?

• Upwards

• In the opposite direction that the object moves.

• In the same direction that the object moves.

• In a direction perpendicular to the direction that the object moves.

When a 45 N object falls to the ground from a height of 4.6 m, how much work is done by the force of gravity?

• 207 Nm

• 304 Nm

• 416 Nm

A weightlifter is holding a 200-kg barbell at a height of 1 meter above the ground. How much work is he performing while holding the barbell still?

• 0 Joules

• 200 Joules

• 1,960 Joules

• 2,000 Joules

In order for Work to happen, what 2 things must occur?

• Mass and Displacement
• Force and Mass
• Force and Work
• Force and displacement

What is the Force equation?
W= 

• F * d * cos(θ)
• m * a
• d / V
• F/ d * cos(θ)

True or false: the net work done on a body is equal to its change in kinetic energy.

• True
• False

What is the total mechanical energy for the position of the ball indicated by the blue circle?

• 0 J

• 50 J

• 100 J

What is the total mechanical energy that the ball would have when it is in the position indicated by the blue circle?

• 0 J

• 50 J

• 100 J

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

How is work defined?

• the amount of energy 
• the transfer of force over a distance
• rate of work in a given time
• the change in distance in a given time