Question

A constant horizontal pull acts on a sled on a horizontal frictionless ice pond. The sled starts from rest. When the pull acts over a distance x, the sled acquires a speed v and a kinetic energy K. If the same pull instead acts over twice this distance, A) The sled’s speed will be 2v and its kinetic energy will be 2K.
B) The sled’s speed will be 2v and its kinetic energy will be K 2 .
C) The sled’s speed will be v 2 and its kinetic energy will be 2K.
D) The sled's speed will be v 2 and its kinetic energy will be K 2 .
E) The sled's speed will be 4v and its kinetic energy will be 2K.

Answer 1

Answer:

K'= 2 K

v'= v√2

Explanation:

As we know that

From work power energy

Work done by all the force = Change in kinetic energy

F . x = K

When distance become 2 x

Then

F.2 x = K'

K' = 2 F . x

K'= 2 K

We know that

$K=\dfrac{mv^2}{2}$

$K'=\dfrac{mv'^2}{2}$

K'= 2 K

$2\dfrac{mv^2}{2}=\dfrac{mv'^2}{2}$

v'²= 2 v²

v'= v√2