Answer: It's the third one.
Explanation:
the football player has speed
Answer:
C. 0 J
Explanation:
When an object moves in a circle, friction provides the centripetal force. Hence, it is acting towards the centre of the circle. The displacement of the object is tangential to the circle at the point of interest. Hence, the angle between the frictional force and the displacement is 90°.
Work done is given by
<em>W</em> = <em>Fd</em> cos <em>θ</em>
where <em>F</em> is the force, <em>d</em> is the displacement and <em>θ</em> is the angle between them.
<em>W</em> = <em>Fd</em> cos 90° = 0 J
Hence, the work done by friction is 0 J.
Moral science is social sciences or philosophy.
That's it, really!
Answer:
The work done by gravity is 784 J.
Explanation:
Given:
Mass of the block is, 
Height to which it is raised is, 
Acceleration due to gravity is, 
Now, work done by gravity is equal to the product of force of gravity and the distance moved in the direction of gravity. So,

Force of gravity is given as the product of mass and acceleration due to gravity.
. Now,

Therefore, the work done by gravity is 784 J.