Question

PLZ TELL ME ANSWER OF THIS PYQ OF CLASS 11​

Answer 1

Answer: 60 m.

Explanation:

A to B:- (A = initial height, B = horizontal glass plate.)

Initial velocity = 0 m/s

Final velocity (at B) = v (let)

Acceleration = g = + 10 m/s² (D)

Time = 6 s

Now we know,

v = u + at

=> v = 0 + (10 m/s²)(6 s)

=> v = 60 m/s.

B to C:- (B = h.g.p., C = earth.)

As per question,

Velocity lost = 2/3 v

∴ Velocity after crash = v - 2/3 v = 1/3 v = 20 m/s = U (let it be the initial velocity for this case)

Time taken to reach ground = 2 s

Acceleration = g = + 10 m/s² (D)

We know,

h = ut + 1/2 gt²

So,

h (height of h.g.p.) = Ut + 1/2 gt² =

=> h = (20 m/s)(2 s) + 1/2 (10 m/s²)(2 s²)

=> h = (40 m + 20 m) = 60 m.

So, height of horizontal glass plate from ground is 60 m.