Answer:
I am not a driver, but I think it's C.
Explanation:
Answer:
d) The trampoline pushes back up on the gymnast.
Explanation:
According to Newton's third law of motion; for every action force, there is an equal and opposite reaction force. The action force and reaction force are reciprocal to one another i.e. they act oppositely to one another. The reaction force acts in an opposite direction to the action force and vice versa.
In this question, a gymnast pushed down on a trampoline during a routine. This is called the ACTION FORCE. In conformity to Newton's third law, the trampoline pushes back up on the gymnast. This opposite force is called the REACTION FORCE.
Answer: A reference point
Explanation: If an object is in motion then its distance from another object is changing. Whether an object is moving or not depends on your point of view. For example, a woman riding on a bus is not moving in relation to the seat she is sitting on, but she is moving in relation to the buildings the bus passes. A reference point is a place or object used for comparison to determine if something is in motion. An object is in motion if it changes position relative to a reference point. You assume that the reference point is stationary, or not moving.
Answer:
35.14°C
Explanation:
The equation for linear thermal expansion is 
, which means that a bar of length 
with a thermal expansion coefficient 
under a temperature variation 
will experiment a length variation 
.
We have then = 0.481 foot, = 1671 feet and = 0.000013 per centigrade degree (this is just the linear thermal expansion of steel that you must find in a table), which means from the equation for linear thermal expansion that we have a 
= 22.14°. As said before, these degrees are centigrades (Celsius or Kelvin, it does not matter since it is only a variation), and the foot units cancel on the equation, showing no further conversion was needed.
Since our temperature on a cool spring day was 13.0°C, our new temperature must be 
= 35.14°C
W=(75kg)(9.8m/s^2
W = 735N
