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Which of the following is an example of work being done on an object?
A.
A man pushes a couch across the room.
B.
A prism scatters ultraviolet light into visible light.
C.
A box rests on the floor.
D.
Water in a pot changes into steam.
In the diagram above, which letter identifies an axle?
A.
X
B.
Z
C.
Y
D.
W
Which simple machine can be described as a shaft that is attached to the center of a wheel?
A.
lever
B.
inclined plane
C.
pulley
D.
wheel and axle
Usually, levers are used to reduce the input force needed to move an object. This is only possible when the input force acts over a long distance and the object moves a shorter distance.
However, sometimes levers are designed to increase the input force needed to move an object. Which of the following is most likely an example of this type of lever?
A.
a catapult
B.
a see-saw
C.
a wheelbarrow
D.
a crowbar
Which of the following is an example of work being done on an object?
A.
A man pushes a couch across the room.
B.
A prism scatters ultraviolet light into visible light.
C.
A box rests on the floor.
D.
Water in a pot changes into steam.
In the diagram above, which letter identifies an axle?
A.
X
B.
Z
C.
Y
D.
W
Which simple machine can be described as a shaft that is attached to the center of a wheel?
A.
lever
B.
inclined plane
C.
pulley
D.
wheel and axle
Usually, levers are used to reduce the input force needed to move an object. This is only possible when the input force acts over a long distance and the object moves a shorter distance.
However, sometimes levers are designed to increase the input force needed to move an object. Which of the following is most likely an example of this type of lever?
A.
a catapult
B.
a see-saw
C.
a wheelbarrow
D.
a crowbar
1 answer:
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Answer:
c)the gravitational forces of people is so small it is overshadowed by that of earth.
Explanation:
The gravitational force between two objects is given by:
where
G is the gravitational constant
m1 and m2 are the masses of the two objects
r is the distance between the two objects
From the formula, we see that the gravitational force depends on the masses of the objects: since the mass of the Earth ( is much much larger than the average mass of one person (80-100 kg), then the gravitational force exerted by the Earth on a person is also much much larger than the gravitational force between two people.
Answer:
The magnitude of the frictional force between the car and the track is 367.763 N.
Explanation:
The roller coster has an initial gravitational potential energy, which is partially dissipated by friction and final gravitational potential energy is less. According to the Principle of Energy Conservation and Work-Energy Theorem, the motion of roller coster is represented by the following expression:
Where:
,
- Initial and final gravitational potential energy, measured in joules.
- Dissipated work due to friction, measured in joules.
Gravitational potential energy is described by the following formula:
Where:
- Mass, measured in kilograms.
- Gravitational constant, measured in meters per square second.
- Height with respect to reference point, measured in meters.
In addition, dissipated work due to friction is:
Where:
- Friction force, measured in newtons.
- Travelled distance, measured in meters.
Now, the energy equation is expanded and frictional force is cleared:
If ,
,
,
and
, then:
The magnitude of the frictional force between the car and the track is 367.763 N.
This is the explanation
