Question

Please give me solution step wise for this question

Answer 1

Tension is a pulling force. Hence minimum tension is observed when the ball is at its highest point and maximum tension is observed when it is at its lowest point.

The forces acting on the ball when it is at its max height and min height will be tension weight and centripetal acceleration

When the ball is at its max height the centripetal acc. will be acting upwards, tension downwards and weight downwards hence the equation at that point will be centripetal acc.=minimum tension+weight--------1

And the equation at its lowest point will be centripetal acc.+weight=max tension which can be written as centripetal acc.+weight=3 min tension(Tmax=3Tmin)-----2

centripetal acc. is given by $mv^{2}/r$

substituting and equating we get weight=centripetal acc.

ie. mg=m$v^{2}$/r

implies g=$v^{2}/r$

hence v=√g*r

g=9.8 and r=20/100(in m)

v=1.4m/s

HOPE IT HELPS

Answer 2

for rotational motion centripetal force is required .therefore.
F=mv^2÷r we know that F=mg therefore you get
mg=mv^2÷r
m will cancel with m and equation will become
g=v^2÷r
v^2=g÷r
v=square root g÷r

now given data is
d=20cm
d=0.2m
but this is diameter to convert it into radius divide diameter by 2
r=d÷2 =0.2÷2 =0.1m
put into equation v=square root g÷r
v=square root 10÷0.1
v=square root 100
v=10m/s