Why does a moving object gain energy?

In summary, the conversation discusses the concept of kinetic energy and how it relates to an object in motion. One of the hints to a problem states that "An object in motion always gains kinetic energy," which leads to confusion about the use of the word "gains." The conversation clarifies that an object only gains kinetic energy if its mass or velocity, or both, increase. It also points out that an object moving with constant velocity does not gain kinetic energy, and suggests that the original hint may have meant to say "An object set in motion always gains kinetic energy." The conversation concludes by questioning the grammar of the hint and speculating that it may be translated from another language.
  • #1
ppppparker
18
4

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

 
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  • #2
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.
 
  • #3
... 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
 
  • #4
They say it gains KE because it started from rest KE=0 and ended up with velocity V and KE=m(v^2)/2.
 
  • #5
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?
 
  • #6
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..
 
  • #7
ppppparker said:
this problem says "An object in motion always gains kinetic energy,
Perhaps it meant to say, "An object set in motion always ..."
 
  • #8
Could you post a link? I can't find that sentence in the likely sections I've looked through.
 

Related to Why does a moving object gain energy?

1. Why does a moving object gain kinetic energy?

When an object is in motion, it possesses kinetic energy due to its velocity. This energy is the result of the object's mass and the speed at which it is moving. The faster an object moves, the greater its kinetic energy will be.

2. How does an object's mass affect its energy when in motion?

The mass of an object has a direct impact on its kinetic energy. A heavier object will have a greater amount of energy when moving at the same speed as a lighter object. This is because the mass of an object determines the amount of force needed to accelerate it to a certain velocity. Therefore, a heavier object needs more energy to reach the same speed as a lighter object.

3. What is the relationship between an object's velocity and its kinetic energy?

The velocity of an object has a direct relationship with its kinetic energy. As the velocity of an object increases, its kinetic energy also increases. This is because an object's kinetic energy is directly proportional to the square of its velocity. In other words, a small increase in velocity can result in a significant increase in kinetic energy.

4. Can an object gain energy without being in motion?

Yes, an object can gain energy without being in motion. This can happen through potential energy, which is stored energy that an object possesses due to its position or state. For example, a bow and arrow possess potential energy when the bow is pulled back, and the arrow is loaded. When the arrow is released, this potential energy is converted into kinetic energy, causing the arrow to move with speed.

5. How is the energy of a moving object related to its position?

The energy of a moving object is not directly related to its position. However, the energy of a moving object can be converted into potential energy by changing its position. For example, a car moving at a high speed possesses kinetic energy. When the brakes are applied, the car's kinetic energy is converted into heat energy, and the car comes to a stop. This change in position results in a change in the type of energy the car possesses.

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