Answer:
<em>Only gravity acts on B but there is an additional residual force from the hand on A.</em>
Explanation:
All bodies are constantly under the effect of gravity. Gravity is what gives us weight here on earth. Gravity acts downwards, and helps to decrease the deceleration of a body moving up and accelerating a body that travels downwards. For the ball A, traveling upwards, the upwards movement is due to the force on it impacted on it from the hand. As A tries to go up, gravity tries to decelerate it until it will come to a stop and then fall downwards under gravity. For body B, descending down means that only gravity forces acts on it at that point, if we ignore buoyant forces and air resistance. And B accelerates as it falls down towards the juggler.
A yo yo in someone’s hand. All of the other options are kinetic energy. Remember, potential energy is when things are at a stop. Kinetic energy is when things are moving.
Answer:
Explanation:
Given
mass of object is m
Mass of planet is M
radius of planet is R
Total Energy associated with mass m at a height h above planet is Gravitational Potential Energy which is given by
![E_1=-\frac{GMm}{R+h}](https://tex.z-dn.net/?f=E_1%3D-%5Cfrac%7BGMm%7D%7BR%2Bh%7D)
When it falls on earth with some velocity v
=Kinetic Energy+Potential Energy
![=\frac{1}{2}mv^2+\frac{-GMm}{R}](https://tex.z-dn.net/?f=%3D%5Cfrac%7B1%7D%7B2%7Dmv%5E2%2B%5Cfrac%7B-GMm%7D%7BR%7D)
As Energy is conserved therefore
![=E_2](https://tex.z-dn.net/?f=%3DE_2)
![\frac{-GMm}{R+h}=\frac{1}{2}mv^2+\frac{-GMm}{R}](https://tex.z-dn.net/?f=%5Cfrac%7B-GMm%7D%7BR%2Bh%7D%3D%5Cfrac%7B1%7D%7B2%7Dmv%5E2%2B%5Cfrac%7B-GMm%7D%7BR%7D)
![\frac{1}{2}mv^2=\frac{GMmh}{R(R+h)}](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B2%7Dmv%5E2%3D%5Cfrac%7BGMmh%7D%7BR%28R%2Bh%29%7D)
![v=\sqrt{\frac{2GMh}{R(R+h)}}](https://tex.z-dn.net/?f=v%3D%5Csqrt%7B%5Cfrac%7B2GMh%7D%7BR%28R%2Bh%29%7D%7D)
Work done = 1/2*(max. force - min. force) * greatest extenstion
Max. force = spring constant * greatest extension= 80*d = 80d N
Min. force = spring constant * smallest extenstion = 80*0 = 0 N
Therefore,
Work done = 1/2*80d*d = 40d^2 J
However,
Mechanical energy = Work done
That is,
0.12 = 40d^2
d = Sqrt (0.12/40) = 0.0548 m
The greatest extension from its equilibrium is 0.0548 m.