Answer: 1.96 m/s
Explanation:
Given
Mass of Professor 
Velocity of professor 
mass of chair 
velocity of chair 
Suppose after the collision, v is the common velocity
Conserving momentum

Answer:Time constant gets doubled
Explanation:
Given
L-R circuit is given and suppose R and L is the resistance and inductance of the circuit then current is given by
![i=i_0\left [ 1-e^{-\frac{t}{\tau }}\right ]](https://tex.z-dn.net/?f=i%3Di_0%5Cleft%20%5B%201-e%5E%7B-%5Cfrac%7Bt%7D%7B%5Ctau%20%7D%7D%5Cright%20%5D)
where
is maximum current
i=current at any time


thus if inductance is doubled then time constant also gets doubled or twice to its original value.
William Gilbert is known as the father of electricity.
Answer:
Moment is the product of force and its perpendicular distance from a point along its line of action.
The net moments on clockwise and anticlockwise is zero at a point.
The net force applied on a spanner handle is equal to the moment of the rotation