# His Kinetic Energy to Kinetic energy of the snow?

• ProPM
In summary, a skier gains kinetic energy as he jumps off a cliff and uses it to do work on the snow when he lands. This energy is eventually transferred to heat due to friction. Similarly, in the cases of a swinging pendulum and a kicked ball, the kinetic energy is used to do work against gravity and is eventually transferred to heat energy through friction.

#### ProPM

I was watching a video and it showed a man going up a hill through a lift. The engine did work on him so he could gain height/GPE energy. Once he got up there they portrayed two scenarios. In the first one he went down like a normal skier.

In the second example, he simply jumped off the cliff and as he lost height, he gained speed and therefore gained KE and when he got to the ground they said the energy was not destroyed, it is used to do work to dig him into the snow. Now, he doesn’t dig himself down forever, he eventually stops. I wanted to know whether he stopped digging down simply because all Kinetic Energy was used doing work (e.g: He had 1000J energy right before he hit the snow and moved 10 m down, he exerted a force of 100 J) but we have to factor in friction doing work against him right? And also, what kind of energy is he transferring? His Kinetic Energy to Kinetic energy of the snow? And the snow stops moving when he stops moving: That’s because of friction too? Basically I'm confused how the skier uses his Kinetic Energy to do work in this scenario.

Thanks

When he lands, the KE is transferred to another form. In this case, heat.

If he has 1000J of kinetic energy on landing, all 1000J are transferred to other forms once stopped. If not, he is still moving.

If you consider the bottom of the hill to be the 0 GPE point, on landing he will have 0 GPE and 0 KE. Which means the energy has gone elsewhere. In this case, it has been transferred to heat through friction with the snow.

To make it easier to understand, consider me stood on a hill. I have 100J of GPE. I jump, that GPE is converted to KE so at the bottom I have 100J of KE. On landing I transfer that KE to heat energy. If you felt the ground it would be ever so slightly warmer because of this.

Ah ok, got it, thanks!

And just one more thing: For example, if I kicked a ball upwards, I would be doing work on it, granting it KE energy. It starts to gain height. Is it using the Kinetic Energy to do work against the force of gravity? Or also, in a Pendulum, when it is at its lowest height it goes up because it uses its KE energy to do work against gravity?

Thanks.

ProPM said:
Ah ok, got it, thanks!

And just one more thing: For example, if I kicked a ball upwards, I would be doing work on it, granting it KE energy. It starts to gain height. Is it using the Kinetic Energy to do work against the force of gravity? Or also, in a Pendulum, when it is at its lowest height it goes up because it uses its KE energy to do work against gravity?

Thanks.

The ball and pendulum:

When you swing the pendulum / kick the ball, you give them a certain amount of KE. It is this energy which does work against gravity.

As they go from the bottom to the maximum height, they have KE. When they reach the top (and stop) they have 0 KE and max GPE. As it starts to descend it loses GPE and gains KE.

The pendulum has maximum KE and minimum GPE at the bottom of its swing and maximum GPE and minimum KE at the top. The pendulum loses energy through mechanical friction, this transfers the KE to heat energy as it moves - eventually stopping it swinging. Note that no energy is lost at the point of 0 KE and max GPE - there is no friction.

This applies to the ball also, but with the ball, once it descends it impacts the floor. At this point the KE becomes heat energy.

for your question. The skier in this scenario is converting his potential energy (GPE) into kinetic energy as he goes down the hill. When he jumps off the cliff, he is converting his potential energy into kinetic energy, and as he falls, this kinetic energy is being transferred to the snow as he digs into it. This is an example of the law of conservation of energy, which states that energy cannot be created or destroyed, only transferred or converted from one form to another.

As the skier digs into the snow, friction does play a role in slowing him down. This is because friction converts some of his kinetic energy into heat energy, which dissipates into the surroundings. This is why the skier eventually stops digging into the snow and comes to a stop.

The type of energy being transferred in this scenario is kinetic energy. The skier's initial kinetic energy is being transferred to the snow, causing it to move and do work (digging him into the snow). This energy transfer is also affected by external forces, such as friction, which can decrease the amount of kinetic energy being transferred.

Overall, the skier is using his kinetic energy to do work by transferring it to the snow. This work is eventually stopped by the forces of friction, which convert some of the kinetic energy into other forms. I hope this helps clarify the concept for you.

## What is kinetic energy?

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

## How is kinetic energy calculated?

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

## What is the difference between kinetic energy and potential energy?

Kinetic energy is the energy an object has due to its motion, while potential energy is the energy an object has due to its position or state.

## How does an object's mass affect its kinetic energy?

The greater the mass of an object, the more kinetic energy it will have if it is moving at the same velocity. This is because mass is a factor in the kinetic energy formula.

## How does the kinetic energy of snow affect its behavior?

The kinetic energy of snow can determine how fast it melts or how far it can travel when thrown. It can also impact the force it exerts when it hits an object, such as a snowball hitting a person. Additionally, the kinetic energy of snow can contribute to avalanches and other natural phenomena.