The speed of an object is measured by calculating the distance it travels per unit time.
The formula in Physics for calculating speed is = distance/ time.
Since an object at rest is not covering any distance, the speed is always assumed to be 0 m/s.
Have you ever been in a bus, a train, or a car ?
What happens to you when it stops suddenly ?
A body in motion continues in motion unless
an external force acts on it and makes it stop.
Amy's body keeps moving forward when the train stops.
She pitches forward, and if she doesn't reach out and grab
a seat or a seated person, she may lose her footing and fall
on her face.
Choice - 'A' is a very good explanation.
The other choices aren't.
'C' is a good hunch, but it only applies to her feet.
The rest of her keeps going.
'D' is nonsense. There are no mysterious forces of
'repulsion' or 'attraction' on the train.
Answer:
A. 0 m/s
Explanation:
The rest frame of an object is defined as the reference frame that is moving together with the object, so at the same speed of the object.
In other words, the rest frame of an object is defined as the reference frame in which the object is at rest, which means that is the reference frame in which the object has speed equal to zero (0 m/s).
Therefore, the correct answer is
A. 0 m/s
Answer:

Explanation:
From the question we are told that:
Period of spring 
Initial Position of Mass 
Final Mass period 
Generally the equation for the Mass location is mathematically given by



Answer:
Explanation:
moment of inertia of reel = 1/2 mr² , m is mass and r is radius of the reel
= .5 x .7 x .0524²
= 96.1 x 10⁻⁵
If force required be F
F x .0524 - 1.88 is net torque acting on the reel
F x .0524 - 1.88 = moment of inertia x angular acceleration.
F x .0524 - 1.88 = 96.1 x 10⁻⁵ x 65.7
F x .0524 - 1.88 = .063
F x .0524 = .063 + 1.88
F = 37.08 N