Give the solution to find the speed of projectile??

Question

A car is moving horizontally along a straight line with a uniform velocity of 25 m/sec.A projectile is to be fired from this car in such a way that it will return to it after it has moved 100 m.Give the solution to find the speed of projectile

Answer 1

time of flight = 100/25 = 4 seconds

So the projectile flight time is 4 seconds and this means 2 seconds up and 2 seconds down.

The initial vertical speed will be:

v = (1/2)gt^2 = (1/2)(9.8)(2^2) = 19.6 m/s

The initial horizontal speed is just the speed of the car since it must reach the car in the same amount of time it takes the car to move the 100 m.

h = 25 m/s

speed = SQRT(h^2 + v^2) = SQRT[(25)^2 + (19.6)^2]

speed = 31.77 m/s

The angle will be:

tan(Angle) = 19.6/25 = 0.784

Angle = 38.1 degrees to the horizontal