Question

A car moving with a velocity of 72 KMPH stops engine just before ascending an inclined road. If 25% of energy is wasted in overcoming friction,the car rises to a height of $(g=10m{s}^2)$

• A. 5 m
• B. 7.5 m
• C. 12 m
• D. 15 m

Answer 1

The correct option is A 5 m

Given that,

Velocity $v=72km/h$

We know that,

The kinetic energy just before approaching the inclined plane 200 m

Now, $25$% of K.E

$=200m\times \frac{25}{100}$

$=50m$

Therefore,

$K.E=P.E.....\left(I\right)$

Let the height be h

Then,

The potential energy is

$P.E=mgh$

Now from equation (I)

$mgh=50m$

$h=\frac{50}{10}$

$h=5m$

Hence, the height is $5m$