Question

A 2000 kg car is accelerated uniformly from rest to a speed of 15 m/s in 10 s. What is the magnitude of the unbalanced force acting on the car?

Answer 1

Let's first find the acceleration of the car from the kinematic equation:

$$v=v_0+at,$$ $$a=\dfrac{v-v_0}{t}=\dfrac{15\ \dfrac{m}{s}-0\ \dfrac{m}{s}}{10\ s}=1.5\ \dfrac{m}{s^2}.$$

Finally, we can find the magnitude of the unbalanced force acting on the car from the Newton's Second Law of Motion:

$$F=ma=2000\ kg\cdot 1.5\ \dfrac{m}{s^2}=3000\ N.$$

Answer:

$F=3000\ N.$