Document Sample

```					                                 Answers to worksheets

4-3 Machines
1. Machine: Work

A machine allows you to do work easier by changing the amount OR the direction of the
input force

2. Work Input: Effort Force

The terms work input and effort force both have to do with what the user of the machine puts
into the machine.

Machines with a mechanical advantage greater than 1 will increase the effort force (input
force). or in other words. The number of times a machine multiplies the effort force is called

4. Work Input: Work Output

Work output can never-ever be greater than work input in a machine. Machines don’t
increase work.

5. Efficiency: Work Output

Efficiency is directly related to work output. The more work output from a machine the
greater its efficiency. You divide work output by the work input to calculate efficiency.

6. Work Output: Resistance Force

The work output of a machine overcomes the resistance force, which is the force that eh
machine is working against.

Activity
Odd Term Out

1. wedge, pulley, inclined plane, screw      A pulley is not a type of inclined plane like all the
others are.

2. sled, barber’s chair, rescue ladder, auto lift   A sled doesn’t lift things like the others do.
3. work input, buoyancy, efficiency, work, output     Buoyancy is a force, everything else is
work-related.

4. Mechanical advantage, joule/sec, power, watt     The three terms all have to do with power.
MA has no effect on power.

5. ramp, fulcrum, lever, seesaw    A ramp is an inclined plane. All the other terms have to do
with levers

6. Newton-meter, watt, joule, work    A Watt is the unit for power. All the other terms relate to
work and the equation for work

7. shovel, steering wheel, block and tackle, typewriter   A typewriter is a compound machine,
whereas all the others are simple machines.

8. machine, multiplies force, multiplies work, redirects force Machines cannot multiply work.
That would be breaking the laws of physics. Work is energy and you can’t create energy, you
can only change its forms.

9. greatest efficiency, least friction, most friction, well lubricated   Having a machine that is
well lubricated will give you the greatest efficiency by causing the least friction….not the most
friction.

10. density= volume/mass, work= force X distance, power= work/time, efficiency = work
output/work input Density is a property of matter that has nothing to do with work or power or
efficiency.

```
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
 views: 25 posted: 11/10/2011 language: English pages: 2