Answer:
The book remained in its state of rest before the car started to move forward as no direct force acted on it.
Explanation:
According to Newton's first law of motion, a body will continue in its present state of rest, or if it is in motion, will continue to move with uniform speed in a straight line unless aced upon by an external force. This tendency of a body to remain in its state of reset or uniform motion in a straight line is known as inertia and is directly proportional to the mass of the body. The more massive a body, the more inertia it possesses. Thus Newton's first law is also known as the law of inertia.
Considering the case of the book on the dashboard of a stationary car which suddenly starts to move. While the car is stopped at the traffic light, the dashboard where the book sits and the book are both at rest. When the car begins to move forward, the dashboard moves forward with it. However as the book is not a part of the car, no force is directly acting on it, so the book so it stays at rest due to its inertia.
Therefore, as the car is moving forward, the stationary book appears to move backward from the reference point of the car, sliding off the dashboard.
Answer:
The tension in the string connecting block 50 to block 51 is 50 N.
Explanation:
Given that,
Number of block = 100
Force = 100 N
let m be the mass of each block.
We need to calculate the net force acting on the 100th block
Using second law of newton



We need to calculate the tension in the string between blocks 99 and 100
Using formula of force


We need to calculate the total number of masses attached to the string
Using formula for mass


We need to calculate the tension in the string connecting block 50 to block 51
Using formula of tension

Put the value into the formula



Hence, The tension in the string connecting block 50 to block 51 is 50 N.
To determine the object which could give the greatest impact we will apply the concept of momentum. The object that has the highest momentum will be the object that will impact the strongest. Our values are
Mass of Object A

Velocity of object A

Mass of object B

Velocity of object B

The general formula for momentum is the product between mass and velocity, then

For each object we have then,


Since the momentum of object A is greater than that of object B, then object A will make you feel force upon impact.