After a short time, the moving sled with the child aboard reached a rough level surface that exerts a constant frictional force
of 54 Newtons on the sled. How much work must be done by friction to bring the sled with the child to a stop
2 answers:
Answer:
Wf = –750J
Explanation:
The full solution can be found in the attachment below.
This problem involves the concepts of conservation of momentum and energy.
The potential energy of the sled and child combined is constant since thehy are moving in a level surface.
To find the initial velocity of the sled with child we use the principle of momentum conservation to calculate the v1 which is the commovelocity of the child and sled.
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Answer:
Explanation:
Torque is defined as the cross product between the position vector ( the lever arm vector connecting the origin to the point of force application) and the force vector.
Due to the definition of cross product, the magnitude of the torque is given by:
Where is the angle between the force and lever arm vectors. So, the length of the lever arm (r) is minimun when
is equal to one, solving for r:
Answer:
-6112.26 J
Explanation:
The initial kinetic energy, is given by
} where m is the mass of a body and
is the initial velocity
The final kinetic energy, is given by
where
is the final velocity
Change in kinetic energy, is given by
Since the skater finally comes to rest, the final velocity is zero. Substituting 0 for and 12.6 m/s for
and 77 Kg for m we obtain
From work energy theorem, work done by a force is equal to the change in kinetic energy hence for this case work done equals <u>-6112.26 J</u>