Explanation:
We will calculate the gravitational potential energy as follows.

= 
= 1164000 J
or, = 1164 kJ (as 1 kJ = 1000 J)
Now, we will calculate the change in potential energy as follows.

=
= 
= -873000 J
or, = -873 kJ
Thus, we can conclude that change in gravitational potential energy is -873 kJ.
Answer:
B.The charge on A is -q; there is no charge on B.
Explanation:
We are given that
Charge=+q
We have to find the correct statement.
When positive charge is placed at center of uncharged metal sphere
insulated from the ground then negative charge(-q) induced on inner
surface A of sphere and the outer surface B is grounded then the surface is neutral .
It means there is no charge on surface B.
Hence, option B is true .
B.The charge on A is -q; there is no charge on B.
Answer:
a) 2.5 m/s²
b) 6.12 m/s
Explanation:
Tension of rope = T = 356N
Weight of material = W = 478 N
Distance from the ground = s = 7.5 m
Acceleration due to gravity = g = 9.81 m/s²
Mass of material = m = 478/9.81 = 48.72
Final velocity before the bundle hits the ground = v
Initial velocity = u = 0
Acceleration experienced by the material when being lowered = a
a) W-T = ma
⇒478-356 = 48.72×a

⇒a = 2.5 m/s²
∴ Acceleration achieved by the material is 2.5 m/s²
b) v²-u² = 2as
⇒v²-0 = 2×2.5×7.5
⇒v² = 37.5
⇒v = 6.12 m/s
∴ Velocity of the material before hitting the ground is 6.12 m/s