The power is calculated using the formula:
Power = Work / Time
where Work = Force * Distance , therefore:
Power = Force * Distance / Time
Power = Force * Velocity<span>
Converting the velocity in units of m/s:</span>
Velocity = (5km / h) (1000m / km) (1h / 3600s)<span>
Velocity = 1.39 m/s
The force is equal to the y-component of the hikers weight:</span>
Force = Wy * g = W * sin θ * g
Let us first find the angle θ. By definition the
slope is equivalent to:
slope = tan θ = ratio of vertical and horizontal
distance
tan θ = 0.09
θ = 5.14˚
Therefore, Force = 68 kg * sin(5.14˚) * 9.8 m/s^2<span>
Force = 666.4 * sin (5.14) = 59.73 N
</span>
<span>Calculating for
power:
<span>Power = 59.73 N * 1.39 m/s = 82.96 W
Since the hikers efficiency is 25%, to determine the metabolic
power:
<span>
Metabolic Power = 82.96 W / 0.25 = 331.83 watts </span></span></span>
Assuming that the gravitational field strength is 10 N/kg, the sum would look like this:
PEg=mgh
=60×10×10
=6000J
However, you will need to check that you are not meant to be using 9.8 N/kg as the gravitational field strength.
Answer: - 7500N
Explanation:
Given the following :
Initial Velocity of car = 108km/hr
Time taken to stop after applying brakes = 4s
Mass of passengers in car = 1000kg
Force exerted by the brakes on the car =?
After 4s, then final Velocity (V) = 0
Initial Velocity (u) of the car = 108km/hr
108km/hr = (108 × 1000)m ÷ (3600)s = 30m/s
Force exerted = mass(m) × acceleration(a)
Acceleration of car = Change in Velocity with time
a = (v - u) / t
a = (0 - 30) / 4
a = - 30/ 4
a = - 7.5m/s^2
Therefore,
Force exerted = mass(m) × acceleration(a)
Force exerted = 1000kg × (-7.5)m/s^2
Force exerted = - 7500N
This should be true, howl this helps