F = m • a
What we know:
- Gravity: 9.8 m/s
- Force: 490 N
Equation derived:
m = F/a
m = 490/9.8
= 50 kg
To find this we should use the equation Ek=1/2mv^2 where Ek is the kinetic energy, m is the mass and v is the velocity. So by this Ek=1/2*1*30^2 which then makes Ek=450 joules
Answer:
The speed of the bob when it passes the lowest point 
Explanation:
Given data

When a pendulum swinging back & forth then at highest point the velocity is zero and lowest point velocity is maximum.
Velocity at lowest point is given by



Therefore the speed of the bob when it passes the lowest point 