Answer : The acceleration of the elevator is, 
Explanation :
Formula used to calculate the acceleration of the elevator is:

where,
F = force = 844 M
m = mass of man = 70 kg
g = acceleration due to gravity = 
a = acceleration of the elevator = ?
Now put all the given values in the above formula, we get:



Thus, the acceleration of the elevator is, 
The frequency is. 1/18. per second.
D
The comet has no net force acting on it, which results in constant velocity. Near our solar system, the influence of the gravitational forces due to the sun and the planets will increase as we know that gravitational force is:
F = GMm/r²
The net force will produce an acceleration on the comet, which will cause its velocity to change.
Answer:
The wavelength of wave is 2.78 m.
Explanation:
Frequency of a wave is 90 Hz
Speed of a wave is 250 m/s
It is assume to find the wavelength of wave. The formula of speed is given by :

So, the wavelength of wave is 2.78 m.