2/7 Science Midterm Review

Work and Power

100

work = ___ times ___

force times distance

200

Power is how _______ work is done

quickly 

300

What is the equation for power? 

power = ... 

power = work / time 

400

650 J of work is done by moving a desk a distance of 5 m. How much force is used? INCLUDE UNITS 

130 N

500

If two people mow two lawns of equal size and person A does the job in half the time as person B, who did more work? Who had more power? 

Same work, person A had more power

Mechanical Energy

100

potential energy + kinetic energy = ___________

mechanic energy

200

Kinetic energy is the energy stored in a _______ object 

moving

300

What is the equation for potential energy? 

potential energy = ... 

mass X gravity x height 

400

What is the equation for kinetic energy? 

kinetic energy = ... 

1/2 x mass x velocity²

500

The law of conversation of energy states that energy can change from one form to another, but it cannot be _____ or _____

destroyed or created

Simple Machines

100

What is a device that makes work easier? 

machine

200

True or false: Machines can reduce both force and displacement at the same time. 

false

300

A ramp is an example of an... 

a. wedge

b. screw

c. inclined plane 

d. pulley

inclined plane 

400

This machine is made up an inclined plane wrapped around a cylinder. 

screw

500

This is a wheel with a groove that changes the direction of the force 

pulley

Levers

100

True or false: to use the least effort, the fulcrum should be placed as far as possible to the load. 

False

200

A lever has a rod that rests and turns about a fixed point, called a ____

fulcrum

300

Scissors are an example of a which type of lever? 

first class lever

400

Which type of lever does NOT save labor? 

third class levers

500

Draw a picture of a first, second, and third class lever with the fulcrum (F), effort (E), and load (L) labeled. 

1st: L F E

2nd: F L E

3rd: L E F

Methods of Separation

100

This method works by heating a mixture until the liquid solvent turns into a gas. 

evaporation

200

True or false: solvent extraction considers the solubility of the substances in the mixture. 

True

300

This method uses a condenser to cool gas until it turns back into a liquid. 

a. evaporation

b. distillation

c. paper chromatography

d. solvent extraction

distillation 

400

Which method works by dissolving part of the mixture but not ALL of it?

a. evaporation

b. distillation

c. chromatography

d. solvent extraction

d. solvent extraction

500

Which method works because of different boiling points of substances? 

distillation