Test Physics

Question 1

Define power and give its formula

Answer 1

A quantity that measures the rate at which work is done

P=w/t

Question 2

What is a machine

Answer 2

A device that changes force

Question 3

What are 3 ways that machines make work easier

Answer 3

• changes the size of force needed
• the direction of a force
• the distance over which a force acts

Question 4

Define Mechanical Advantage

Answer 4

A quantity that measures how much a machine multiplies force or distance

Question 5

What is efficiency

Answer 5

A quantity usually expressed as a percentage that measures the ratio of used work input

Question 6

Formula for efficiency

Answer 6

E=useful work output/work input

Question 7

What can’t efficiency equal 100%

Answer 7

Friction

Question 8

Simple machine

Answer 8

One of the six basic types of machines

Question 9

What two families are simple machines divided into

Answer 9

Lever
And
Inclined plane

Question 10

Compound machines

Answer 10

A machine that is made of more than one simple machine

Ex: scissors, jacks, bicycle

Question 11

Define levers

Answer 11

A rigid bar that is free to move around a fixed point

Question 12

What classes are levers divided into?

Answer 12

1st class levers
2nd class levers
3rd class levers

Question 13

Wheel and axel

Answer 13

Simple machine that consists of two disks or cylinders each one with a diff radius

Question 14

Define inclined planes

Answer 14

Slanted surface along which a force moves an object to a diff elevation

Question 15

Define pulleys

Answer 15

A simple machine that consists of a rope that fits into a groove in a wheel

Question 16

What are the 3 types of pulleys?

Answer 16

Fixed pulleys,moveable pulleys, pulley systems

Question 17

All levers have a rigid arm that turns around a point called the ______

Answer 17

Fulcrum

Question 18

First class levers

Answer 18

• fulcrum is in the middle of an arm
• the input force acts on one end
• the other end applies an output force
• MA can be 1, =1

Ex: Tetter totter

Question 19

Second class lever

Answer 19

• fulcrum is at one end of the arm
• input force is applied to the other end
• output force is in the middle
• MA will always be greater than 1

Ex: wheel barrow

Question 20

Third class lever

Answer 20

• input force is in the middle
• output force is on one end
• fulcrum is on the other end
• multiply distance rather than force
• MA always

Question 21

Define work and give its formula

Answer 21

A quantity of energy transferred by a force when it is applied to a body and causes that body to move in the direction of the force

W=f*d