# What is the original kinetic energy of the player?

• needhelp83
In summary, kinetic energy is the energy an object has due to its motion, calculated using the equation KE = 1/2 * m * v^2. The unit of measurement is joules, but it can also be measured in other units. In the context of a player, kinetic energy refers to their energy from movement on the field or court. Factors such as mass, speed, external forces, surface, and technique can affect a player's kinetic energy.
needhelp83
A 95-kg football player traveling 5.0 m/s is stopped in 1.0 s by a tackler.
a. What is the original kinetic energy of the player?
b. What average power is required to stop him?

a.
K=(1/2)mv2
K=(1/2)(9500 g)(5.0 m/s)2= 118,750 J
b.
P=w/t
P=118750 J/1.0 s= 118750 W

Would this be correct because of the work-energy principle?

Looks okay, but I don't see why you should convert [kg] to [g].

Yes, your calculations for the original kinetic energy and average power are correct based on the work-energy principle, which states that the work done on an object is equal to its change in kinetic energy. In this case, the work done by the tackler to stop the player is equal to the player's initial kinetic energy.

## 1. What is kinetic energy?

Kinetic energy is the energy that an object possesses due to its motion. It is a scalar quantity and is dependent on the mass and velocity of the object.

## 2. How is kinetic energy calculated?

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

## 3. What is the unit of measurement for kinetic energy?

The SI unit for kinetic energy is joules (J). However, it can also be measured in other units such as calories or electron volts.

## 4. How does kinetic energy relate to the movement of a player?

In the context of a player, kinetic energy would refer to the energy they possess due to their movement on the field or court. It would be influenced by their mass and the speed at which they are moving.

## 5. What factors can affect the original kinetic energy of a player?

The original kinetic energy of a player can be affected by their mass, speed, and any external forces acting on them such as friction or air resistance. Additionally, factors such as the surface they are playing on and their technique can also impact their kinetic energy.

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