Question about power and output power.

[vegetables102]

1. How could you measure your output power developed while pushing a car?


2. If you developed a certain amount of power running up let's say 2 flights of stairs, could you develop the same power if you ran up twice as many stairs?


3. What factors affect a persons output power running up stairs?

 

[mafagafo]

You need to try to solve the problem before we can help you. Show us your progress.

 

[dean barry]

1.
Rough guess :
Level road assumed, tyres at recommended pressure.

m = mass of the car in kg
g = local gravity rate ( use 9.81 (m/s)/s )
Crr = tyre on ashphalt rolling resistance co-efficient ( use 0.03 )

Rolling resistance force (f) ( constant, regardless of speed ) = m * g * Crr
( answer is in Newtons )

Find the maximum speed (v) you can push the car in metres per second
(mph * 0.44704 = metres per second)

Then :
The power provided (W) to push the car :
W = f * v
(answer is in Watts, divide by 745.7 to get horsepower)

Example :
v = maximum push speed = 4 m/s (example)
m = 1,500 kg
g = 9.81 (m/s)/s
Crr = 0.03

f = m * g * Crr
f = 1,500 * 9.81 * 0.03
f = 441.45 Newtons

W = f * v
W = 441.45 * 4
W = 1,765.8 Watts ( about 2.37 hp )

2.
Energy change (Joules) = m * g * h
m = your mass in kg
g = local gravity rate (use 9.81 (m/s)/s)
h = vertical height moved in metres (floor to floor difference)
Then :
Average Power = energy change / time in seconds
3.
Power output is roughly proportional to your size, but includes factors like sex, fitness level, nutrition etc.

 

[BvU]

Hello vegie, and welcome to PF.

You show us the questions that were put to you. Which question are you putting to PF ?

Anyway, for # 1 I would use a scale between my hands and the car to have guess for the force. Push a certain distance in a certain time and there you are !

(How many tyres does Dean's car have? And does he really think he can push hard enough to get a meaningful furlongs/fortnight -- oh, sorry, mph -- reading from the speedometer ?)

Share your work, Veggie !

 

[HalfLostAndSearching]

1. To measure your output power while pushing a car, you could use a dynamometer. A dynamometer is a device that measures the force and torque applied by an object. By attaching the dynamometer to the car and pushing with a constant force, you can determine the amount of power you are exerting. Alternatively, you could also use a power meter, which measures the amount of energy being produced by the body during the pushing motion.

2. No, you would not be able to develop the same power if you ran up twice as many stairs. Power is the rate at which work is done, and running up more stairs would require more work to be done in the same amount of time. Therefore, the power output would increase as the amount of work increases.

3. There are several factors that can affect a person's output power while running up stairs. These include the individual's physical fitness, body weight, and muscle strength. Additionally, the speed and technique used while running up stairs can also impact the power output. For example, taking longer strides and using more forceful movements can increase power output. The type of surface and incline of the stairs can also play a role in the amount of power needed to ascend them.