Two stones are thrown towards each other simultaneously, one vertically downwards from the top of the tower of height 360 m with velocity 10 m/s and other from the ground vertically upwards with velocity 50 m/s. Find the time and the distance from the ground at which they collide. [Take, g = 10 m/s2]
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Answers
Answer:
While both the stones are in flight, a
1
=g and a
2
=g
So a
rel
=0⇒V
rel
=constant
⇒X
rel
=(const)t
⇒Curve ofx
rel
v/s t will be straight line.
After the first particle drops on ground, the seperation (x
rel
) will decrease parabolically (due to gravitational acceleration),
and finally becomes zero.
and V
rel
=slope of x
rel
v/st
Given :-
▪ Two stones are thrown towards each other simultaneously. One vertically downwards from the top of the tower of height h = 360 m with velocity v₁ = 10 m/s and other from the ground vertically upwards with velocity v₂ = 50 m/s.
▪ Acceleration due to gravity, g = 10 m/s²
To Find :-
▪ Time taken and the distance from the ground at which they will collide.
Solution :-
Here, We take every measurements in upward direction positive while measurements in downward direction negative.
From these, we have
- g = -10 m/s²
- v₁ = - 10 m/s²
Now, Let us find the relative velocity, since they are in opposite direction, hence the velocities would be added. (Including gravity)
⇒ v = v₁ + v₂
⇒ v = 10 + 50
⇒ v = 60 m/s
The time taken to cover the distance 360 m with this velocity is actually the time at which it will collide.
⇒ Time taken, t = 360 / 60
⇒ t = 36/6
⇒ t = 6 s
So, Let us find the distance from the ground at which they will collide.
⇒ s = ut + 1/2 gt²
⇒ s = 50 × 6 + 1/2 × -10 × 6²
⇒ s = 300 - 5×36
⇒ s = 300 - 180
⇒ s = 120 m
Hence, They will collide after 6 s and at a distance of 120 m from the ground.