Question

Ball X is vertically up at the same time as ball Y is projected horizontally, If air
resistance is negligible and both start from the same height:
a) X and Y will reach the level ground at the same time
b) X will reach the level ground first
c) Y will reach the level ground first
d) We must know the mass of X and Y to tell which will hit the ground first
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Answer 1

Answer:

(a) X and Y will reach the level ground at the same time

Explanation:

ball x is at height h then it's initial vertical velocity will be zero and ball y is projected horizontally so it will have some initial velocity in horizontal but in vertical direction it will have zero velocity.

so both have same vertical velocity and same vertical acceleration due due to gravity and time of flight depend upon initial vertical velocity ,height and acceleration. and these quantity are same for both partical so time of flight will be same.