Question

A small ball of mass m is released in a smooth
circular tube as shown in figure. The minimum height
h such that bead can complete the circle is
7m
'R
(1) 2.5R
(3) 1.5R
(2) 2R
(4) R​

Answer 1

Answer: 2.5R

Explanation: MARK ME AS BRAINLIST

V = root 5gr

U Square = 0

a = g

S = h

By v square = u Square + 2gh

5gr = 0 + 20h

50r/20 = h

h = 2.5r

Answer 2

Given that,

Mass of ball = m

We know that,

The velocity at the bottom is

$v = \sqrt{5gr}$

We need to calculate the height

Using equation of motion

$v^2=u^2+2gh$

Put the value into the formula

$5gR=0+2gh$

$h=2.5 R$

Hence, The minimum height is 2.5 R.

(1). correct option.