Two grenades, A and B, are thrown horizontally with different speeds from the top of a cliff 70 m high. The speed of A is 2.50 m/s and the speed of B is 3.40 m/s. Both grenades remain in air for 3.77 s. Assume that the acceleration due to gravity is 9.86 m/s^2. What is the distance between A and B if they are thrown along the same straight line?

Question

Two grenades, A and B, are thrown horizontally with different speeds from the top of a cliff 70 m high.  The speed of A is 2.50 m/s and the speed of B is 3.40 m/s.  Both grenades remain in air for 3.77 s.  Assume that the acceleration due to gravity is 9.86 m/s^2.  What is the distance between A and B if they are thrown along the same straight line?

MathMate · Answer

The horizontal distances are given by
Da(t) = 2.5t m
Db(t) = 3.4t m
Distance between A and B after 3.77 seconds is therefore
Distance = Db(3.77)-Da(3.77)
assuming the grenades are thrown in the same straight line in the same direction.
The acceleration due to gravity has no bearing on the distance between A and B, if air resistance can be ignored.