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SIMPLE MACHINES
Using the guide above, identify the fulcrum, output force, input force, and type of lever
for the following items below:
MECHANICAL ADVANTAGE
1. A machine uses an input force of 200 newtons to produce an output force of 800
newtons. What is the mechanical advantage of this machine?
2. A machine is required to produce an output force of 600 newtons. If the machine has a
mechanical advantage of 6, what input force must be applied to the machine?
3. A machine with a mechanical advantage of 10 is used to produce an output force of
250 newtons. What input force is applied to this machine?
WORK
1. For the following situations, determine whether work was done. Write “work done” or “no
work done” for each situation.
a. An ice skater glides for two meters across ice.
b. The ice skater’s partner lifts her up a distance of 1 m.
c. The ice skater’s partner carries her across the ice a distance of 3 m.
d.After setting her down, the ice skater’s partner pulls her across the ice a distance of 10 m
e. After skating practice, the ice skater lifts her 20-N gym bag up 0.5 m.
2. You pull your sled through the snow a distance of 500 m with a horizontal force of 200
N. How much work did you do?
3. A bulldozer does 30,000. J of work to push another boulder a distance of 20. m. How
much force is appliedto push the boulder?
POTENTIAL AND KINETIC ENERGY
1. Determine the amount of potential energy of a 5.0-N book that is moved to three
different shelves on a bookcase. The height of each shelf is 1.0 m, 1.5 m, and 2.0 m.
2. What is the kinetic energy of a 2,000.-kg boat moving at 5.0 m/s?
3. What is the velocity of a 500-kg elevator that has 4000 J of energy?
4. What is the mass of an object traveling at 30. m/s if it has 33,750 J of energy?
ENERGY TRANSFORMATIONS
Read each scenario below.
• Identify which of the following forms of energy are involved in the scenario:
mechanical, radiant, electrical, chemical, and nuclear.
• Make an energy flow chart that shows how the energy changes from one form to
another, in the correct order.
1. A camper is using a wood fire to heat up a pot of water for tea. The pot has a whistle
that lets the camper know when the water boils.
2. The state of Illinois generates some of its electricity from nuclear power. A young
woman in Chicago is watching a broadcast of a sports game on television.
3. A bicyclist is riding at night. He switches on his bike’sgenerator so that his headlight
comes on. The harder he pedals, the brighter his headlight glows.
ENERGY EFFICIENCY
1. A professional cyclist rides a bicycle that is 92 percent efficient. For every 100 joules
of energy he exerts as input work on the pedals, how many joules of output work are used
to move the bicycle?
2. An automobile engine is 15 percent efficient. How many joules of input work are
required to produce 15,000 joules of output work to move the car?
3. It takes 56.5 kilojoules of energy to raise the temperature of 150 milliliters of water
from 5 °C to 95 °C. If you use an electric water heater that is 60% efficient, how many
kilojoules of electrical energy will the heater actually use by the time the water reaches
its final temperature?
POWER
1. A motor does 5,000. joules of work in 20. seconds. What is the power of the motor?
2. A 1000-watt microwave oven takes 90 seconds to heat a bowl of soup. How many
joules of energy does it use?
3. A force of 100. newtons is used to move an object a distance of 15 meters with a
power of 25 watts. Find the work done and the time it takes to do the work.