Chapter 2, Problem 1Q

(a)

To determine

The change that happens to the magnitude of the momentum when the net force acts in the +x direction and $F$ is constant.

Answer to Problem 1Q

The magnitude of the momentum will remain same when the net force acts in the +x direction and $F$ is constant .

Explanation of Solution

Write the expression for the force according to Newton’s second law.

    $F=\frac{dp}{dt}$        (I)

Here, $F$ is the force, $\frac{dp}{dt}$ is the rate of change in momentum.

Conclusion:

Since the force is constant and acting in the x direction, the magnitude of the momentum remains same whereas the direction will change.

(b)

To determine

The change that happens to the magnitude of the momentum when the net force acts in the +x direction and $F$ is increasing.

Answer to Problem 1Q

The magnitude of the momentum will increase since the net force acts in the +x direction and $F$ is increasing.

Explanation of Solution

Write the expression for the force according to Newton’s second law.

    $F=\frac{dp}{dt}$

Since $F$ and $p$ are directly proportional, increase in the magnitude of force will increase the magnitude of momentum.

Conclusion:

Since the magnitude of the momentum will increase since the net force acts in the +x direction and $F$ is increasing.

(c)

To determine

The change that happens to the magnitude of the momentum when the net force acts in the +x direction and $F$ is decreasing

Answer to Problem 1Q

The magnitude of the momentum will decrease since the net force acts in the +x direction and $F$ is decreasing

Explanation of Solution

Write the expression for the force according to Newton’s second law.

    $F=\frac{dp}{dt}$

Since $F$ and $p$ are directly proportional, decrease in the magnitude of force will decrease the magnitude of momentum.

Conclusion:

Since the magnitude of the momentum will decrease since the net force acts in the +x direction and $F$ is decreasing.

(d)

To determine

The change that happens to the magnitude of the momentum when the net force acts in the +-x direction and $F$ is constant.

Answer to Problem 1Q

The magnitude of the momentum will remain same since the net force acts in the -x direction and $F$ is constant

Explanation of Solution

Since the net force is in the negative x direction, the initial and final momentum will be acting in the same direction and since the force is constant the magnitude will be same only.

Conclusion:

Since The magnitude of the momentum will remain same since the net force acts in the -x direction and $F$ is constant

(e)

To determine

The change that happens to the magnitude of the momentum when the net force acts in the -x direction and $F$ is increasing.

Answer to Problem 1Q

The magnitude of the momentum will remain decrease since the net force acts in the -x direction and $F$ is increasing.

Explanation of Solution

Since the net force is in the negative x direction, the initial and final momentum will be acting in the same direction and as the force is increasing the magnitude of momentum will decrease.

Conclusion:

Since the magnitude of the momentum will remain decrease since the net force acts in the -x direction and $F$ is increasing.

(f)

To determine

The change that happens to the magnitude of the momentum when the net force acts in the -x direction and $F$ is decreasing

Answer to Problem 1Q

The magnitude of the momentum will remain decrease since the net force acts in the -x direction and $F$ is decreasing.

Explanation of Solution

Since the net force is in the negative x direction, the initial and final momentum will be acting in the same direction and as the force is decreasing the magnitude of momentum will increase.

Conclusion:

Since the magnitude of the momentum will remain decrease since the net force acts in the -x direction and $F$ is decreasing.