Question

A truck starts from rest and rolls down a hill with a constant acceleration. It travels a distance of $400m$ in $20s$. Find its acceleration. Find the force acting on it if its mass is $7metrictons$ (Hint: $1metricton=1000kg$).

Answer 1

Step 1: Given

Distance traveled, $s=400m$

Time taken, $t=20s$

Mass of the truck, $m=$$7metrictons=7000kg$

Initial velocity, $u=0m{s}^{-1}$

Step 2: Formula used and calculation

$s=ut+\frac{1}{2}a{t}^2$

Where “a” is the acceleration.

Step 3: Calculating the acceleration

Using the equation of motion

$$\begin{gathered} s=ut+\frac{1}{2}a{t}^2 \\ \Rightarrow 400m=0\times 20s+\frac{1}{2}a\times {\left(20\right)}^2 \\ \Rightarrow a=\frac{400\times 2}{20\times 20} \\ \Rightarrow a=2m{s}^{-2} \end{gathered}$$

Hence, the acceleration of the truck is $2m{s}^{-2}$.

Step 4: Calculating the net force

Now, force is given by

$$\begin{gathered} F=ma \\ \Rightarrow F=7000kg\times 2m{s}^{-2} \\ \Rightarrow F=14000N \end{gathered}$$

Hence, the force acting on the truck is $14000N$.