Answer: 
Explanation:
This problem can be solved by the following equation:

Where:
is the change in kinetic energy
is the electric potential difference
is the electric charge
Finding
:


Finally:

Answer:
Explanation:
height of pole = 15 ft
height of man = 6 ft
Let the length of shadow is y .
According to the diagram
Let at any time the distance of man is x.
The two triangles are similar

15 y - 15 x = 6 y
9 y = 15 x

Differentiate with respect to time.

As given, dx/dt = 4 ft/s

ft/s
Answer:

Explanation:
The angular momentum of the pulsar is given by:

where
is the mass of the pulsar
is the radius
is the angular speed
Given the period of the pulsar,
, the angular speed is given by

And so, the angular momentum is

Answer:
B
Explanation:
Acceleration = rate of change in velocity
a = (21-12)/(0.45) = 20cm/s^2
The term period (symbol: T) describes the time it takes for an object to complete one full cycle of motion on a spring.
The formula for time is: T = 1 / f , where f is the frequency , f= c / λ = wave speed c (m/s) / wavelength λ (m)..
The formula describes that as the frequency of a wave increases, the time period of the wave decreases.