Power, mass, speed, time and height

In summary, a child of 30 kg runs up a flight of stairs in 6 seconds, reaching a speed of 2ms^-1 at the top. The top of the flight is 3 metres above the bottom. To calculate the average power needed, you can use the work-energy equations and the vertical displacement. The child likely starts from rest and accelerates uniformly to reach their given speed at the top.
  • #1
furor celtica
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Homework Statement


A child of mass 30 kg runs up a flight of stairs in 6 seconds. The top of the flight is 3 metres above the bottom, and at the top he is running at 2ms^-1. What average power does he need to produce?



The Attempt at a Solution



This is one of the first exercises I have had to tackle concerning power, so I'm pretty sure its meant to be simple. However, in terms of power both force x velocity and work/time i have no idea where to start.

Without the child's starting speed, horizontal distance covered or total distance run I'm at a loss for what to use and what to look for...any suggestions would help.

Homework Equations

 
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  • #2
The problem is vague about the child's initial speed. I assume since it gives the velocity at the top of the stairs and it talks about average power, that the child starts from rest and accelerates uniformly to reach her given speed at the top.

Buy you don't need horizontal or total distance to find work...you just need the vertical displacement...think about the work- energy equations.
 

Related to Power, mass, speed, time and height

1. What is the relationship between power and mass?

The relationship between power and mass can be described by the equation P = m x a, where P is power, m is mass, and a is acceleration. This means that the power of an object is directly proportional to its mass and acceleration. In other words, the greater the mass of an object, the more power is required to accelerate it.

2. How does speed affect an object's kinetic energy?

Speed directly affects an object's kinetic energy, which is the energy an object has due to its motion. The kinetic energy of an object is calculated using the equation KE = 1/2 x m x v^2, where m is mass and v is velocity. This means that as an object's speed increases, its kinetic energy also increases.

3. How is time related to speed and distance?

Time is directly related to both speed and distance. This can be understood using the equation d = v x t, where d is distance, v is speed, and t is time. This means that the distance an object travels is equal to its speed multiplied by the time it takes to travel that distance.

4. How does height affect an object's gravitational potential energy?

The gravitational potential energy of an object is directly affected by its height. The higher an object is elevated above the ground, the greater its gravitational potential energy. This can be calculated using the equation PE = m x g x h, where m is mass, g is gravitational acceleration, and h is height.

5. What is the formula for calculating power?

The formula for calculating power is P = W/t, where P is power, W is work, and t is time. This means that power is equal to the amount of work done divided by the time it takes to do that work. Power is commonly measured in watts (W) or horsepower (hp).

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