In object in motion stays in motion; speed
Answer:
Centripetal acceleration.
Explanation:
Centripetal acceleration is a property of a body moving in a uniform circular path and it is directed radially towards the center of the circle in which body is rotating.
The force which causes this acceleration is centripetal force which is also directed towards the center of the circle and pulls the body towards its center.
It is calculated through following formula

where v is velocity and r is the radius of the circle.
Velocity = displacement/time
1.6 = 253/t
t = 158.125
It takes them about 158 seconds
Answer:
The velocity of the freight car decreases.
Explanation:
This question is answered by the conservation of momentum principle.
When the freight car is moving at a certain speed, it has a constant momentum.
We will call this M1.
The equation for M1 will be:
M1 = Mass * Speed
Now when the coal is dumped into the freight car, the Mass increases.
Since conservation of momentum states that the momentum will remain the same. We have:
M1 = (Mass of freight + Mass of coal) * Speed
Since M1 is constant, if the mass increases, the speed had to decrease to keep the equation true.
The force applied to an object is said to be a product of its mass and the acceleration. For this case, acceleration is the reading on the gravitometer. We calculate as follows:
F = mg
39.36 N = m(9.83 m/s^2)
m = 4.00 kg
Hope this answers the question. Have a nice day.