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.
The answer is “D. all of the above”!
Metal from the paper clip is attracted to the magnet, so it will naturally move toward and stick to the magnet. This will cause the paper clip to temporarily become a magnet for other metals. I hope this helped!
Answer:
The electric field will be zero at x = ± ∞.
Explanation:
Suppose, A -2.0 nC charge and a +2.0 nC charge are located on the x-axis at x = -1.0 cm and x = +1.0 cm respectively.
We know that,
The electric field is

The electric field vector due to charge one

The electric field vector due to charge second

We need to calculate the electric field
Using formula of net electric field


Put the value into the formula




Put the value into the formula


If x = ∞, then the equation is be satisfied.
Hence, The electric field will be zero at x = ± ∞.
Answer:
8 seconds
Explanation:
power (P) is defined as the rate at which work is done.
power is measured in Watts (W) , when the work done is measured in Joules (J) and time in seconds
by the definition of power,
