Work
Mixed
Machines
Random
Calculation
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Question: Work - 10
• Using the scientific definition of work,
which of the following is TRUE?
A. It is difficult.
B. It involves levers.
C. It involves a transfer of energy.
D. It is done with a machine.
Answer:Work– 10
C. It involves a transfer of energy
Question: Work - 20
• In order for work to be done, an object
must ____________________.
A. Have mass
B. Move in the direction of the applied
force
C. Have muscles
D. Move at a right angle to the force
Answer: Work – 20
B. Move in the direction of the applied
force
Question: Work- 30
An object is moving due east. You push the
object. Work is being done at all times
when you push ________________.
A. due west
C. straight down
B. due east
D. at a 45˚ angle
Answer: Work – 30
B. due east
Question: Work - 40
• NO work is being done on a ball when
you _____________ the ball.
A. hit
C. carry
B. catch
D. drop
Answer: Work– 40
D. drop
Question: Work - 50
• SI unit for work
Answer: Work – 50
• Joules
Question: Mixed - 10
• ___________________ describes the
rate at which work is done.
A. Joules
B. Power
C. Force
D. Efficiency
Answer: Mixed – 10
• B. Power
Question: Mixed - 20
• a pivot point of a lever
Answer: Mixed – 20
• A fulcrum
Question: Mixed- 30
• SI unit for power
Answer: Mixed – 30
• Watt
Question: Mixed- 40
• has only one movement
Answer: Mixed – 40
A simple machine
Question: Mixed - 50
• Exertion of force on an object that
produces motion in the direction of the
force
Answer: Mixed– 50
• Work
Question: Machines - 10
• In an ideal machine, which of the
following is TRUE?
A. Work input is equal to work output.
B. Work input is greater than work
output.
C. Work input is less than work output.
D. The IMA is always equal to 1.
Answer: Machines– 10
• A. Work input is equal to work output.
Question: Machines- 20
• Which of these is NOT done by a
machine?
A. Multiply force
B. Multiply energy
C. Change direction of the force
D. Increase the distance of the force
Answer: Machines – 20
• B. Multiply energy
Question: Machines - 30
• A __________ is an example of a
compound machine.
A. lawnmower
C. baseball bat
B. shovel
D. wheel and axle
Answer: Machines – 30
• A. lawnmower
Question: Machines - 40
• Machines let you use less force over a
greater _________.
A. distance
C. weight
B. mass
D. direction
Answer: Machines– 40
• A. distance
Question: Machines- 50
• When Egyptians built the pyramids, they
used the idea that a LARGE FORCE over a
SHORT DISTANCE can be accomplished by
the same work as a SMALL FORCE over a
___________________ distance.
A. Changing
B. Minimum
C. Shorter
D. Larger
Answer: Machines– 50
• D. Larger
Question: Random- 10
• a device that makes work easier by
changing the size or direction of the
applied force
Answer: Random– 10
• A machine
Question 4 - 20
• the number of times a machine
multiplies the input force
Answer: Random– 20
• Mechanical advantage
Question: Random - 30
• two rigidly attached wheels that rotate
together
Answer: Random – 30
• Wheel and axle
Question: Random- 40
• a machine’s ability to convert work input
into work output
Answer: Random – 40
• Efficiency
Question: Random - 50
• an inclined plane wrapped around a shaft
Answer: Random – 50
• A screw
Question: Calculation - 10
• What is the power used if it took 2,000 J
to move a box in 8 s?
Answer: Calculation – 10
P= w/t
= 2000/8 = 250 W
Question: Calculation- 20
How much work is done lifting a 9.10 kg
box onto a shelf 1.8 m high?
Answer: Calculation – 20
W=F x d
= (9.1 x 9.8) x 1.8 = 160.5 J
Question: Calculation - 30
A ramp is 2.8 m long and 1.2 m high. How
much power is needed to push a box up
the ramp in 4.6 s with a force of 96 N?
Answer: Calculation – 30
P= w/t …but first find w.
W= F x d = 96 x 2.8 = 268.8 J
The distance you are
moving the box
So P= w/t = 268.8/ 4.6 = 58.4 W
Question: Calculation - 40
• What is the efficiency of a machine if the
work input is 75 N and the work output is
25N?
Answer: Calculation – 40
Efficiency = output/input x 100
= (25/ 75) x 100
= 33%
Question 5 – 50
Surprise short answer!!
If a machine cannot have more work
output than work input, what advantage is
there to using one?
Answer 5 – 50
• A machine increases the amount of
force that you apply to the machine.
For example, the force you apply to a
car jack will lift a car whereas you
may not be able to lift the car
without one.