A slide with a frictionless curved surface, which becomes horizontal at its lower end, is fixed on the…

A slide with a frictionless curved surface, which becomes horizontal at its lower end, is fixed on the terrace of a building of height 3h from the ground, as shown in the figure. A spherical ball of mass m is released on the slide from rest at a height h from the top of the terrace. The ball leaves the slide with a velocity u0=u0x and falls on the ground at a distance d from the building making an angle θ with the horizontal. It bounces off with a velocity v and reaches a maximum height h1. The acceleration due to gravity is g and the coefficient of restitution of the ground is 13. Which of the following statement(s) is(are) correct?

  1. u0=2ghx
  2. v=2ghx-z
  3. θ=60o
  4. dh1=23

Solution

Using energy conservation,

mgh=12mu02

u0=2gh

u0 is the horizontal component of the velocity throughout the flight. For vertical component of the velocity(just before collision with the ground), we can use equation of motion

vz2=02+2-g-3hvz=6gh

Angle θ can be written as,

tanθ=vzu=3

θ=60o

Horizontal distance covered just before the collision will be,

d=u0T=u023hg=2gh23hg=23h

After collision, only velocity along z-direction changes. Therefore,

v1=evz=2gh and hence

v=u0i+v1k

=2ghi+k=2ghx+z

Now, maximum height achieved after collision will be,

h1=v122g=h.

Finally, u0=2gh, θ=60o, dh1=23.

Asked in: JEE Advanced 2023 (Paper 1)

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