Download Unit 3 Test [23291]

Unit 3 Test [23291]
Student
Class
Date
Instructions
Choose the best answer. When you are finished, please sit quietly.
1.
Using Figure 14-4, if the downward force was applied by you for a distance of 2 m, how much work would
you have done?
A.
12.5
B.
50 J
C.
12.5 J
D.
12.5 W
2. What is the mechanical advantage of the lever in figure 14-4?
A.
9
Unit 3 Test
Page 1/15
B.
5750
C.
9.2
D.
0.109
3. The watt and the horsepower are both units of
4.
A.
mechanical advantage
B.
efficiency
C.
work
D.
power
For work to be done on the object, the object has to
A.
have a force applied to it
B.
have friction
C.
be efficient
D.
move
Unit 3 Test
Page 2/15
5.
6.
7.
You calculate work by multiplying the ___ acting in the direction of motion by the ___ the object moves.
A.
force/time
B.
force/distance
C.
work/distance
D.
work/time
The rate at which work is done is called __
A.
power
B.
force
C.
mechanical advantage
D.
efficiency
What is the mechanical advantage of the ramp below?
Unit 3 Test
Page 3/15
8.
9.
A.
0.308
B.
3.25
C.
468
D.
32.5
A device that changes the size or direction of force used to do work is called a(an) ___
A.
motor
B.
mechanical advantage
C.
machine
D.
force
Why is the work output of a machine always less than the work input?
A.
Some of the work output is used for power.
B.
Some of work input is used to overcome friction
C.
A machine cannot help you do work.
Unit 3 Test
Page 4/15
D.
Some of the work output increases friction
10. The SI unit of power is the
11.
12.
A.
joule
B.
watt
C.
newton-meter
D.
newton
If you grease a ramp to make a box slide more easily, what happens to the ramp’s mechanical
advantage?
A.
it stays the same
B.
it decreases
C.
it is multiplied by 100
D.
it increases
Any part of a force that does not act in the direction of an object’s motion does no ___ on the object.
Unit 3 Test
Page 5/15
A.
power
B.
efficiency
C.
mechanical advantage
D.
work
13. If you exert a force of 850 N to walk 5.5 m up a flight of stairs in 25 s, how much power do you use?
A.
3863.64W
B.
6.18 W
C.
18.7 W
D.
187 W
14. Why don’t you do work as you hold a book motionless over your head?
A.
Because no machine is helping you
B.
The book is the one doing the work
C.
There is no movement so no work is done.
Unit 3 Test
Page 6/15
D.
15.
Gravity is doing the work
What is the unit of work?
A.
horsepower
B.
watt
C.
joule
D.
all of the above
16. A worker uses a cart to move a load of bricks a distance of 10 m across a parking lot. If he pushes the cart
with a constant force of 209 N, what amount of work does he do?
A.
2090 W
B.
2090 J
C.
20.9 W
D.
20.9 J
17. The force that you exert on a machine is called the __ force.
Unit 3 Test
Page 7/15
18.
A.
input
B.
work
C.
power
D.
watt
A girl lifts a 160-N load a height of 1 m in a time of 0.5 s. What power does the girl produce?
A.
80 J
B.
320 W
C.
320 J
D.
80 W
19. The force that is exerted by a machine on an object is called the ___ force.
A.
output
B.
friction
C.
mechanical
Unit 3 Test
Page 8/15
D.
input
20. An example of a compound machine is a
A.
bicycle
B.
crowbar
C.
ramp
D.
seesaw
21. A bar that is free to pivot about a fixed point is a ____.
A.
fulcrum
B.
lever
C.
ramp
D.
screw
22. An inclined plane wrapped around a cylindrical post is a ____.
A.
block and tackle
Unit 3 Test
Page 9/15
23.
24.
B.
lever
C.
ramp
D.
screw
Two simple machines that are part of a bicycle are a(n)____.
A.
gear and a wheel and axle
B.
inclined plane and a lever
C.
inclined plane and a wedge
D.
screw and an inclined plane
How can a machine make work easier for you?
A.
by decreasing the amount of work you do
B.
by changing the direction of your force
C.
by increasing the work done by the machine
D.
none of the above
Unit 3 Test
Page 10/15
25. Which of the following is an example of a wheel and axle?
26.
27.
A.
hammer
B.
an automobile steering wheel
C.
a jar lid
D.
a pencil
3 m/s north is an example of a(n) ____.
A.
speed
B.
velocity
C.
position
D.
acceleration
The relationship among mass, force, and acceleration is explained by ____.
A.
conservation of momentum
Unit 3 Test
Page 11/15
B.
Newton's First Law of Motion
C.
Newton's Second Law of Motion
D.
Newton's Third Law of Motion
28. The size of the gravitational force between two objects depends on their ____.
A. frictional forces
B.
inertia
C.
masses and the distance between them
D.
speed and direction
29.Suppose
you increase your jogging speed from 2 m/s to 4 m/s in a period of 2s. What is your
acceleration?
A.
2 m/s2
B.
1 m/s2
C.
4 m/s2
D.
3 m/s2
Unit 3 Test
Page 12/15
30. An orange might roll off your cafeteria tray when you stop suddently because of
A.
the balanced forces acting on the orange
B.
the centripetal force acting on the orange
C.
the friction forces acting on the orange
D.
the orange's inertia
31. A feather will fall thorugh the air more slowly than a brick because of ________________
A.
air resistance
B.
gravity
C.
inertia
D.
momentum
32. The statement "to every action there is an equal and opposite reaction" is
______________________.
A.
the law of conservation of momentum
Unit 3 Test
Page 13/15
B.
Newton's First Law of Motion
C.
Newton's Second Law of Motion
D.
Newton's Third Law of Motion
33. As an astronaut travels far away from Earth, her weight
A.
decreases because gravity decreases
B.
decreases because her mass decreases
C.
increases because gravity increases
D.
remains the same because her mass remains the same.
34. In the absence of air, a penny and a feather that are dropped from the same height at the same
time will __________________.
A.
fall at different rates
B.
fall at the same rate
C.
float
D.
not have momentum
Unit 3 Test
Page 14/15
35. Inertia varies depending on
A.
force
B.
mass
C.
velocity
D.
motion
Unit 3 Test
Page 15/15