Calculating Energy Transfer for 75kg Boy Sliding Down Hill

[phys1618]

Homework Statement

75 kg boy, starting from rest, slides down a 30 degrees hill htat is 70 m long. He arrives a thet bottom with a speed of 15 m/s. How much thermal energy has been shared btwn the surface of the hill and the seal of his pants

Homework Equations

d=(vf2-vi2)/2a
KE=1/2Mv2
change of ENERGYsystem=constant
PEi +KEi=PEf + KEf
PE=Mgh

The Attempt at a Solution

I have no clue to figure this out...please help by explaining the steps..Many thanks!

 

[LowlyPion]

Homework Statement

75 kg boy, starting from rest, slides down a 30 degrees hill htat is 70 m long. He arrives a thet bottom with a speed of 15 m/s. How much thermal energy has been shared btwn the surface of the hill and the seal of his pants

Homework Equations

d=(vf2-vi2)/2a
KE=1/2Mv2
change of ENERGYsystem=constant
PEi +KEi=PEf + KEf
PE=Mgh

The Attempt at a Solution

I have no clue to figure this out...please help by explaining the steps..Many thanks!

Figure what his PE was. Then figure what his KE is at the bottom. The difference went into warming his behind.

 

[thomate1]

I can help you calculate the energy transfer for this scenario. First, we need to understand the different types of energy involved in this situation. The boy has potential energy (PE) at the top of the hill due to his position, and as he slides down, this potential energy is converted into kinetic energy (KE). Additionally, there is friction between the boy's pants and the surface of the hill, which converts some of the kinetic energy into thermal energy.

To calculate the potential energy of the boy at the top of the hill, we can use the equation PE = mgh, where m is the mass of the boy (75 kg), g is the acceleration due to gravity (9.8 m/s^2), and h is the height of the hill (70 m). This gives us a potential energy of 51,450 Joules.

Next, we can use the equation KE = 1/2mv^2 to calculate the kinetic energy of the boy at the bottom of the hill. We know that the boy has a mass of 75 kg and a speed of 15 m/s, so his kinetic energy is 8,437.5 Joules.

Since energy is conserved, the change in energy of the system (the boy) is equal to the difference between the initial and final energies. In this case, the change in energy is equal to the boy's initial potential energy (51,450 J) minus his final kinetic energy (8,437.5 J), which gives us 43,012.5 Joules.

However, not all of this energy goes into the boy's kinetic energy. Some of it is transferred into thermal energy due to the friction between his pants and the hill. This amount of thermal energy can be calculated by subtracting the boy's final kinetic energy from the change in energy of the system. In this case, it would be 43,012.5 J - 8,437.5 J = 34,575 Joules.

Therefore, the amount of thermal energy shared between the surface of the hill and the boy's pants is approximately 34,575 Joules. Keep in mind that this is an estimate and the actual amount may vary depending on factors such as the type of surface and the material of the boy's pants.