Question

A car of mass 1500kg is moving with a certain velocity, u. It is brought to rest by the application of brakes, within a distance of 20m when the average resistance being offered to it is 60000N.What was the velocity of the motor car?

• A. 20 m/s
• B. 30 m/s
• C. 40 m/s
• D. 50 m/s

Answer 1

The correct option is C

40 m/s

F = ma $\Rightarrow$ a= $\frac{60000}{1500}$ = 40 $m/s^2$
Now,
$v^2=u^2+2as$
$\Rightarrow$ $u^2=2\ast 40\ast 20$
$\Rightarrow$ u = 40m/s