Σf = m a
Σf = m v^2 / r
Σf = 52 8^2 / 1.6
Σf = 2080 N
Answer:
Tension, T = 0.0115 N
Explanation:
Given that,
Mass of the plastic ball, m = 1.1 g
Length of the string, l = 56 cm
A charged rod brought near the ball exerts a horizontal electrical force F on it, causing the ball to swing out to a 21.0 degree angle and remain there. According to attached figure :

T is tension in the string

So, the tension in the string is 0.0115 N.
Velocity, va2 = 10.5 ft/s
<u>Explanation:</u>
From the figure:
Length of the cable = Sa + 2Sb = l
∴ vₐ = -2vb
Applying the principle of Impulse and momentum in x-direction

Limit is t1 to t2
-(1)
Applying the principle of Impulse and momentum in y-direction

Limit is t1 to t2
-(2)
Solving equation (1) and (2), we obtain
T = 1.6lb
va2 = 10.5 ft/s