Answer:

Explanation:
The string theory is a theoretical concept, the very small particles of particle physics are rep[laced by strings. This theory also applies to black hole physics, nuclear physics, cosmology etc.
According to string theory, six space-time dimensions cannot be measured except as quantum numbers of internal particle properties because they are curled up in size of the order of
.
The length of the scale is assumed to be on the order of
. Hence, the correct option is (a).
Given :
The acceleration due to gravity on or near the surface of Earth is 32 ft/s/s
To Find :
From what height must a stone be dropped on Earth to strike the ground with a velocity of 136 ft/s.
Solution :
Initial velocity of stone, u = 0 ft/s.
Now, by equation of motion :

Therefore, height from which stone is thrown is 289 ft.
Explanation:
Given parameters:
Force applied = 150N
Time = 2s
Unknown:
Momentum change = ?
Solution:
The momentum change of a body is the difference between its initial and final momentum.
Momentum is the same as the impulse exerted on a body which is the product of force and time
Momentum = mass x velocity = force x time
The body initially at rest has a momentum of 0, as the momentum changes;
Momentum change = Final momentum - initial momentum
= f x t - (0)
= (150 x 2) - 0
Momentum change = 300kgm/s
Since the body is a frictionless surface, the net force is the same as the applied force.
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