Question

A constant net force of 200 N is exerted to accelerate a car from rest to a velocity of 40 m/s. What is the mass of the cart?

Answer 1

From the second Newton's law, the mass of the car is:

$$m = \dfrac{F}{a}$$

where $F=200N$ is the net force, $a$ is the acceleration of the car. By definition, the acceleration is given as follows:

$$a = \dfrac{v-0m/s}{t} = \dfrac{v}{t}$$

where $v = 40m/s$ is the final speed of the car, $0m/s$ is its initial speed (start from rest), and $t$ is the time required to reach the speed $v$.

Thus, obtain:

$$m = \dfrac{Ft}{v}$$

Answer. $m = \dfrac{Ft}{v}$.