Answer:
Explanation:
The rotational kinetic energy remains constant as long as the length and angular speed are fixed.
Statement A is true.
When the ball is pulled inward and the length of the string is shortened, the rotational kinetic energy will remain constant due to conservation of energy,
Statement B is false .
Reason - Conservation of energy will not be there because external work is done on the system by the force that pulls it inward.
but the angular momentum L will not remain constant because there is an external force acting on the ball to pull it inward
Statement C is false .
Reason - the angular momentum L will remain constant because there is an external force acting on the ball which acts perpendicular to the velocity of the ball .
The moment of inertia I remains constant
Statement D is false
Reason - because distance from axis of rotation is changing.
the angular speed will remain the same throughout the process because the ball is rotating in the same plane throughout the motion.
Statement E is false
Reason - Since moment of inertia decreases , to conserve angular momentum , angular speed increases.
Answer:
a) 
b) 
Explanation:
Given:
- weight of the stone,
- initial velocity of vertical projection,
- air drag acting opposite to the motion of the stone,
The mass of the stone:
Now the acceleration of the stone opposite of the motion:
where:
d = deceleration
<u>In course of going up the net acceleration on the stone will be:</u>
a)
Now using the equation of motion:
where:
final velocity when the stone reaches at the top of the projectile = 0
h = height attained by the stone before starting to fall down
b)
during the course of descend from the top height of the projectile:
initial velocity, 
The acceleration will be:
here the gravity still acts downwards but the drag acceleration acts in the direction opposite to the motion of the stone, now the stone is falling down hence the drag acts upwards.
Using equation of motion:
(+ve acceleration because it acts in the direction of motion)
Balenced
Think of it this way if 2 same weight and same speed objects were racing toward each other perfectly straight then their forces will cancel out and the movement afterwords will be 0
Answer:
3 * 10³J/s
Explanation:
Given :
Force applied, F = 300 N
Distance, d = 30 m
Time, t = 3 seconds
Power, P = Workdone / time
Recall :
Workdone = Force * distance
Workdone = 300 N * 30 m = 9000 Nm
Workdone = 9 * 10³ J
Power = (9 * 10³ J) / 3s
Power = 3 * 10³J/s
