Question

1. what kind of quantity is momentum?

a. scalar
b. vector

1. when does the net force on an object increase?

a. when \\( \delta p \\) decreases
b. when \\( \delta t \\) increases
c. when \\( \delta t \\) decreases

1. in the equation \\( \delta p=m(\mathbf{v}_{f}-\mathbf{v}_{i}) \\), which quantity is considered to be constant?

a. initial velocity
b. final velocity
c. mass
d. momentum

Explanation:

• Question 21: Momentum is defined as \( \vec{p}=m\vec{v} \), where \( m \) is mass (a scalar) and \( \vec{v} \) is velocity (a vector). The product of a scalar and a vector is a vector.
• Question 22: According to Newton's second law in terms of momentum \( F_{net}=\frac{\Delta p}{\Delta t} \). If \( \Delta t \) (time interval) decreases while \( \Delta p \) (change in momentum) is non - zero, the value of \( F_{net} \) increases.
• Question 23: In the equation \( \Delta\vec{p}=m(\vec{v}_{f}-\vec{v}_{i}) \), when we are considering the change in momentum of an object due to a change in its velocity, the mass \( m \) of the object (assuming it is not changing, e.g., no mass is added or removed from the object) is considered constant.

Answer:

• 21. B. Vector
• 22. C. When \( \Delta t \) decreases
• 23. C. Mass