# Object is accelerated from rest , find KE

• discosucks
In summary, the conversation discusses calculating the kinetic energy of an object that is accelerated from rest by a force of 32 N over a distance of 18 m. The formula for kinetic energy is mentioned, along with the relationship between work and kinetic energy. It is determined that the work done on the object is equal to its final kinetic energy, since its initial kinetic energy is zero.

## Homework Statement

An object is accelerated from rest by a force of 32 N over a distance of 18 m. Calculate the
kinetic energy of the object after 18 m

## Homework Equations

KE = 0.5 • m • v^2[/B]

## The Attempt at a Solution

I can't work out where ill be able to get the mass or the velocity for this one?

discosucks said:
I can't work out where ill be able to get the mass or the velocity for this one?
Hint: Maybe you won't need those quantities. Any other principles you know that have to do with energy?

discosucks said:
I can't work out where ill be able to get the mass or the velocity for this one?

You can work them out if you wish , if we can put 'a' in term of 'm' [From the given force] , we can find the final velocity using the equations of motion with constant acceleration [the acceleration is constant because the force is constant] .

But this method is quite long .However, as Mr @Doc Al said, there is a shorter method that has to do with work and energy , could you figure it out?

:)

ummm

well the force by the distance will give me the work done

32 x 18 = 576J

Im almost sure there is a relationship between work and KE but i can't work out what

Maged Saeed
discosucks said:
ummm

well the force by the distance will give me the work done

32 x 18 = 576J

Im almost sure there is a relationship between work and KE but i can't work out what

Well, have you studied Work-Kinetic energy theorem ?

Yes but I am not sure i totally understand what to do when with the formula we have

That's the formula you need! What does it say? (In words.)

If I am totally honest I am not sure what KEf and KEo stand for .

discosucks said:
If I am totally honest I am not sure what KEf and KEo stand for .

Work-Kinetic energy says :
"For a particle , a change in the kinetic energy equals the net work done on the particle "

In the formula you give :

KEf stands for final kinetic energy of the object.
KE0 stands for initial kinetic energy of the object.

I Hope you get the point now ,,.

Ah so the work done is the same as the KE !

I know the work done is 576J so that's the same as the KE!

Maged Saeed
The work done is equal to the value of KEf - KE0 But KE0 is zero since the object has started from the rest [the velocity is zero] so the final kinetic energy is equal to the work done by the object..:)

Oh perfect i actually over looked that! thaks again for your help!

Maged Saeed

## 1. What is the definition of kinetic energy?

Kinetic energy is the energy an object possesses due to its motion.

## 2. How is kinetic energy calculated?

Kinetic energy (KE) is calculated using the formula KE = 1/2 * m * v^2, where m is the mass of the object and v is the velocity or speed of the object.

## 3. What is the relationship between acceleration and kinetic energy?

The relationship between acceleration and kinetic energy is direct. This means that as the acceleration of an object increases, its kinetic energy also increases. Conversely, as acceleration decreases, so does kinetic energy.

## 4. How does the initial velocity affect the kinetic energy of an object?

The initial velocity of an object does not affect its kinetic energy. Kinetic energy is only dependent on the mass and final velocity of an object.

## 5. Can an object have a negative kinetic energy?

No, an object cannot have a negative kinetic energy. Kinetic energy is always a positive value and represents the energy an object possesses due to its motion.