sorry, it's B, not a made a mistake in the approximation
Answer:
Part a)

Part B)

Explanation:
Part A)
While escalator is moving up work done to move the person upwards is given as

here we know that
m = 63 kg
h = 4.4 m
now we have


Part B)
Work done while we move from up to down
So we have

so we have

External force.
Air resistance, friction, grass rubbing on a rolling ball, etc.
If there is no external force on a moving object, it keeps going.
Forever !
Answer:
10. B
13. It's actually 30 seconds but 20 comes closest so B
14. B, any type of stretching is good before you perform any type of physical activity because it loosens up the muscles
15. D, all of the above
Explanation:
I have done many sports in my life and am still very active, I grew to know most of these things through the years.
Answer:
The answer is 45 degree angle