Answer: 259.2 KJ
Explanation:
The formula calculate work don in a circuit is given by :-
, where Q is charge and V is the potential difference.
The formula to calculate charge in circuit :-
, where I is current and t is time.
Given : Current : 
Potential difference : 
Time : 
Now, 
Then, 
Hence, the work done = 259.2 KJ
Answer: 81.619 kJ
Explanation:
Given
Mass of roller coaster is 
It reaches the steepest hill with speed of 
Hill to bottom is 51 m long with inclination of 
Height of the hill is 
Conserving energy to get kinetic energy at bottom
Energy at top=Energy at bottom

Answer: Option (b) is the correct answer.
Explanation:
The given data is as follows.
F =
N
g = 9.8 m/s
radius =
=
= 15 cm = 0.15 m (as 1 m = 100 cm)
Formula to calculate depth is as follows.
F = 
or, h =
h =
= 751 m
Thus, we can conclude that the maximum depth in a lake to which the submarine can go without damaging the window is closest 750 m.
The answer is :78 I think