Given that,
Electrical energy of the motor = 2280 J
Kinetic energy = 1606 J
Wasted energy in thermal and sound energy = 550 J
To find,
The efficiency of the motor in percent.
Solution,
Efficiency is defined as the ratio of useful output energy to the total energy.
Total energy = 2280 J
Useful energy = 1606 J

So, the efficiency of the motor is 70.43%.
Mike enters a revolving door that is not moving. Mike should
push at the edge of the door where it is largest distance from the pivot point
in order to produce a torque with the least amount of force. Torque is equal to
t = force x distance.
Answer:
a
The orbital speed is 
b
The escape velocity of the rocket is 
Explanation:
Generally angular velocity is mathematically represented as
Where T is the period which is given as 1.6 days = 
Substituting the value


At the point when the rocket is on a circular orbit
The gravitational force = centripetal force and this can be mathematically represented as

Where G is the universal gravitational constant with a value 
M is the mass of the earth with a constant value of 
r is the distance between earth and circular orbit where the rocke is found
Making r the subject
![r = \sqrt[3]{\frac{GM}{w^2} }](https://tex.z-dn.net/?f=r%20%3D%20%5Csqrt%5B3%5D%7B%5Cfrac%7BGM%7D%7Bw%5E2%7D%20%7D)
![= \sqrt[3]{\frac{6.67*10^{-11} * 5.98*10^{24}}{(4.45*10^{-5})^2} }](https://tex.z-dn.net/?f=%3D%20%5Csqrt%5B3%5D%7B%5Cfrac%7B6.67%2A10%5E%7B-11%7D%20%2A%205.98%2A10%5E%7B24%7D%7D%7B%284.45%2A10%5E%7B-5%7D%29%5E2%7D%20%7D)

The orbital speed is represented mathematically as

Substituting value

The escape velocity is mathematically represented as

Substituting values


F = ma
Rearrange this so acceleration is the subject:
A = f/m
Now input your values into this equation for the first question :
A = f/m
A = 15/45
A = 0.33333333 m/s
Then using this same equation change the force of 15 to 25 :
A = f/m
A = 25/45
A = 0.55555556 m/s
For the last question keep the force of 15N but change the mass to 70kg into the same equation :
A = f/m
A = 15/70
A = 0.21 m/s (rounded)
Answer:

Explanation:
We are asked to find the final velocity. We are given the acceleration, time, and initial velocity, so we can use the following kinematics formula.

In this formula,
is the final velocity,
is the initial velocity,
is the acceleration, and
is the time.
The bicycle has an initial velocity of 5.0 m *s⁻¹ or m/s, acceleration of 2 m/s², and a time of 5 seconds.

Substitute the values into the formula.

Solve inside the parentheses.

Add.

The units can also be written as:

The bicycle's final velocity is 15 meters per second.