Question

a car of mass 850kg hits a crash barrier at a speed of 30m/s . the car stops in 0.4s.calculate the force of the car.​

Answer 1

Given :-

• Mass of Car = 850 kg
• initial speed,u = 30 m/s
• Time span in which car stop = 0.4 s

To Find :-

• force on car

Solution:-

During the collision an impulse is created which due to which is equal to change in momentum.

Mathematically,

$\green{ \underline { \boxed{ \sf{Impulse, F\times t = m (v-u) }}}}$

where

• F = force
• t = time span
• m = mass
• v= final speed
• u = initial speed

Now,

$\begin{gathered}\\\implies\quad \sf F \times 0.4 = 850 \times (0-30) \\\end{gathered}$

$\begin{gathered}\\\implies\quad \sf F \times 0.4 = 850 \times -30 \\\end{gathered}$

$\begin{gathered}\\\implies\quad \sf F = -\frac{25500}{0.4} \\\end{gathered}$

$\begin{gathered}\\\implies\quad \sf F = -63750 N \\\end{gathered}$

$\quad\quad\quad\quad\quad\quad$(-ve sign denotes opposite direction)

Therefore, a force of 63750 Newton will act on the car in opposite direction.