Question

a truck is moving at a constant velocity of u=54 km per hour in what direction should the stone be projected up with the velocity of V = 30 metre per second from the floor of the truck as to appear at right angle to the truck for a person standing on the earth​

Answer 1

Answer:

α = cos⁻¹ [-1/2]

Explanation:

Hey,

According to the question,

=> A truck is moving at a constant velocity, u=54 km/h.

∴ 54km/h = 54 * 1000 / 3600 m/s = 15 m/s  [ ∵ 1 km = 1000m, 1h = 3600 sec]

=> Suppose here, the stoneis projected at an angle of 'α' in the same direction of motion of truck with speed of v = 30 m/s.

=>As the resultant displacement along horizontal is equals to zero, the velocity along horizontal is zero too.

∴ Vcosα + 15 = 0

Vcosα = -15

cosα = -15/30   [∵ V = 30m/s]  

∴ α = cos⁻¹ [-1/2]