Question

STUDENT TASK
1.
A ball moving here and there in a smooth circular cap is shown below. The points to which the ball goes
on either side of lowest point B are 10 cm high from B. The speed of ball at B is
C
B
c) 0.7 m/s
d) 14 m/s
a) 1.4 m/s
b) 2.8 m/s
the other end of the string at the​

Answer 1

Mass = m
Gravitational acceleration = g = 10 m/s^2
Height = h = 10cm = 0.1 m ( 1m = 100cm )
Potential energy at Point B = mgh
= m * 10 * 0.1
= m
Therefore total energy at Point B is ‘m’ ( By Conservation of Energy , As here kinetic energy
is 0 )

At point C
the total energy is equal to Kinetic Energy ( By Conservation of Energy , As here potential
energy is 0 )

Kinetic energy = Total energy ( Total energy is always same every where )
1/2mv^2 = m
1/2v^2=1 ( subtracting m from both the side )
v^2 = 2
v = square root of 2
v = 1.4....m/s

Therefore option ‘a’ is correct .

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