Answer:
T = 60 s
Explanation:
There are 6 poles on the track which are equally spaced
so the angular separation between the poles is given as


so the angular speed of the train is given as


now we have time period of the train given as



Answer:
45.6m
Explanation:
The equation for the position y of an object in free fall is:

With the given values in the question the equation has one unknown v₀:

Solving for t=1:
1) 
To find the hight of the tower you can use the concept of energy conservation:
The energy of the body 1 sec before it hits the ground:
2) 
If h is the height of the tower, the energy on top of the tower:
3) 
Combining equation 2 and 3 and solving for h:
4) 
Combining equation 1 and 4:

The weight is 45 N, because the three chains hold the sign, and each contributes 15 N.
Notice that the mass would be the weight/acceleration of gravity, m = 45/9.8 kg. But they ask the weight (force, so Newtons)
Work = force * distance
and newton*meters = Joule
In this case, work = 250N*50m = 12500 J
So the answer is D) 12,500 J