CBSE Class 11-science Answered

Taking the car to be a point as nothing is mentioned in the question about the height of the car or point from which they are projected.

time for projectile to fall on the car is equal to the time taken for car to travel from starting point upto this position.

For car 72 km/h = 20 m/s.

Let car travel through a distance of 500-x and projectile travels through a horizontal distance of x

20 = (500-x)/t ---------(1)

For projectile

x = u cos 45 x t-------------(2)

take t = 2u sin 45/g-----------(3)

use equations 1, 2 and 3 to solve for u.