Question

A car whose total mass is 800kg travelling with a uniform velocity of 20m/s suddenly observes a stationary dog 50m ahead on its path. If the total force applied on the braking system on the car by the driver is 2000N, what would happen? ​

Answer 1

The driver hits the stationery dog because the applied force is less than required force

Step-by-step explanation:

Kinetic energy will be given by

`KE=0.5mv^(2)` where m is the mass of the vehicle and v is the speed/velocity of the vehicle.

Substituting 800 Kg for m and 20 m/s for v we obtain

`KE=0.5*800*(20 m/s)^(2)=160,000`

Frictional force by vehicle pads is given by

`Fr=\frac {KE}{d}` where d is the distance moved

Substituting 160000 for KE and 50 m for d we obtain

`Fr=\frac {160000}{50}=3200 N`

Therefore, the vehicle hits the dog since the required force is 3200N but the driver applied only 2000 N