Answer:

Explanation:
We know that speed is given by dividing distance by time or multiplying length and frequency. The speed of the father will be given by Lf where L is the length of the father’s leg ad f is the frequency.
We know that frequency of simple pendulum follows that 
Now, the speed of the father will be
while for the child the speed will be 
The ratio of the father’s speed to the child’s speed will be

Answer:
Speed of the electron will be 
Explanation:
We have given that charge on electron 
Mass of electron 
Potential difference = 
Now according to energy conservation 


They have different accelerations because of their masses. According to Newton's Second Law, an objects acceleration is inversely proportional to its mass. Therefore the object with the larger mass, in this case the gun, will have a smaller acceleration. In the same way, the less massive object, being the bullet, will have a higher acceleration.
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Answer:
minimum power should be used to operate the air conditioner is 4000 W
Explanation:
given data
students n = 160
power p = 125 W
COP = 5.0
to find out
what minimum power should be used
solution
we know the COP formula that is given below
COP = students × power / minimum power
minimum power = n × p / COP
put all value
minimum power = n × p / COP
minimum power = 160 × 125 / 5
minimum power = 4000 W
minimum power should be used to operate the air conditioner is 4000 W
I attached the missing picture.
We can figure this one out using the law of conservation of energy.
At point A the car would have potential energy and kinetic energy.

Then, while the car is traveling down the track it loses some of its initial energy due to friction:

So, we know that the car is approaching the point B with the following amount of energy:

The law of conservation of energy tells us that this energy must the same as the energy at point B.
The energy at point B is the sum of car's kinetic and potential energy:

As said before this energy must be the same as the energy of a car approaching the loop:

Now we solve the equation for

: