A) it occurs when earth is between the sun and the moon
Answer:
From question (a) and (b) the pendulum motion is perpendicular to the force so the normal force will do no work and the tension in the string of the pendulum will not work

And
so

c
An example will be a where a stone is attached to the end of a string and is made to move in a circular motion while keeping the other end of the string in a fixed position
d
A dog walking along a surface which has friction, here the frictional force would acting in the direction of the motion and this would do positive work
Explanation:
Carbon: C, 12.011, 6, 12
Oxygen: O, 8, 8, 8, 16
Boron: B, 10.811, 5, 5, 11
The answer is B (The second one). I'm not sure though.
Answer:
t = 4.1 seconds
Explanation:
It is given that,
Width of road which is to be crossed by a man is 8.25 m, it means it is distance to be covered.
Speed of man is 2.01 m/s
We need to find the time taken by the man to cross the road. It is a concept of speed. Speed of a person is given by total distance covered divided by time taken. So,

t is time taken

So, the time taken by the man to cross the road is 4.1 seconds.