Why does a moving object gain energy?

[ppppparker]

Homework Statement

One of the hints to this problem says "An object in motion always gains kinetic energy, so the change in energy of an object starting from rest would be P = m(v^2) / (2t)

I understand that a moving object has kinetic energy, but why did they say it gains kinetic energy (or maybe I am not understanding grammar?) thanks for any help

Homework Equations

KE = (1/2) m(v^2)

The Attempt at a Solution

 

[SteamKing]

An object can gain KE only if m or v or both increase. If m = constant and v = constant, then KE must be a constant.

 

[CWatters]

... the change in energy of an object starting from rest would be P = m(v^2) / (2t)

That's not quite correct. P in that equation appears to stand for Power which is the rate of change of KE.

If the object starts at rest and some time t later has velocity V then the change in KE is...

∆KE= m(v^2)/2

 

[CWatters]

They say it gains KE because it started from rest KE=0 and ended up with velocity V and KE=m(v^2)/2.

 

[CWatters]

An object in motion always gains kinetic energy

That's not true. An object moving with constant velocity does not gain KE. It's KE stays the same. Objects only gain KE if the velocity increases.

Are you translating this from another language?

 

[ppppparker]

thats exactly what I've been thinking for a number of questions actually.. the grammar is messing up the questions so i think it must be translated .. but its on Khan academy , kinda surprised me because I thought Khan is a pretty serious site now..

 

[NascentOxygen]

this problem says "An object in motion always gains kinetic energy,

Perhaps it meant to say, "An object set in motion always ..."

 

[Merlin3189]

Could you post a link? I can't find that sentence in the likely sections I've looked through.