a sled and rider with a combined weight 60kg are at rest on the top of a hill 12m high. what is their total energy at the top of the hill?
To calculate the total energy at the top of the hill, we need to consider the potential energy and the kinetic energy.
1. Potential Energy:
The potential energy of an object is given by the formula P.E. = mgh, where m is the mass, g is the acceleration due to gravity (which is approximately 9.8 m/s² on Earth), and h is the height.
In this case, the mass is the combined weight of the sled and rider, which is 60 kg, and the height is 12 m. Therefore, the potential energy is:
P.E. = 60 kg * 9.8 m/s² * 12 m = 7,056 J (joules).
2. Kinetic Energy:
Since the sled and rider are at rest on top of the hill, there is no initial kinetic energy.
Total Energy:
At the top of the hill, the total energy is the sum of the potential energy and kinetic energy. Since there is no initial kinetic energy, the total energy at the top of the hill is equal to the potential energy:
Total Energy = Potential Energy = 7,056 J.
Therefore, the total energy at the top of the hill is 7,056 joules.