Answer:
56 kg
Explanation:
The change in potential energy of the man is given by:

where
m is the man's mass
g is the gravitational acceleration
is the change in height of the man
In this problem, we have:
is the gain in potential energy
g = 9.8 m/s^2 is the gravitational acceleration
is the change in height
Re-arranging the equation and substituting the numbers, we find the mass:

Answer:
See explaination
Explanation:
Please kindly check attachment for the step by step solution of the given problem.
The attached file has a detailed solution of the given problem.
Answer:
Part a)

Part b)

Part c)


Explanation:
Part a)
As we know that frequency = 1 MHz
speed of electromagnetic wave is same as speed of light
So the wavelength is given as



Part b)
As we know the relation between electric field and magnetic field



Part c)
Intensity of wave is given as



Pressure is defined as ratio of intensity and speed


Answer:4.39 s
Explanation:
Given
initial velocity 
acceleration 
velocity acquired by sled in
time


distance traveled by sled in 



distance traveled in
time with velocity 




----1


substitute the value of
in 1
we get

thus 

It would be static friction which is what you have to overcome when an object is not in motion. When you move an object friction works against it like gravity and air resistance. I hope this helps!