Answer:
(a) 
(b) 
(c) K.E. = 21.168 J
(d) 
Explanation:
Given:
- mass of a block, M = 3.6 kg
- initial velocity of the block,

- constant downward acceleration,

That a constant upward acceleration of
is applied in the presence of gravity.
∴
- height through which the block falls, d = 4.2 m
(a)
Force by the cord on the block,



∴Work by the cord on the block,


We take -ve sign because the direction of force and the displacement are opposite to each other.

(b)
Force on the block due to gravity:

∵the gravity is naturally a constant and we cannot change it


∴Work by the gravity on the block,



(c)
Kinetic energy of the block will be equal to the net work done i.e. sum of the two works.
mathematically:


K.E. = 21.168 J
(d)
From the equation of motion:

putting the respective values:

is the speed when the block has fallen 4.2 meters.
'Universe' means 'Everything'. That is, all matter, all space, all time.
Answer:
no the moon does not rotate it only goes in circle just like the sun so I disagree with your friend
Answer:
The acceleration is -9.8 m/s²
Explanation:
Hi there!!
When you throw a ball upward, there is a downward acceleration that makes the ball return to your hand. This acceleration is produced by gravity.
The average acceleration is calculated as the variation of the speed over time. In this case, we know the time and the initial and final speed. Then:
acceleration = final speed - initial speed/ elapsed time
acceleration = -4.3 m/s - 4.3 m/s / 0.88 s
acceleration = -9.8 m/s²