a girl of mass 40 kg is skating at a constant speed of 1 m/s. supposed she doubles her speed, how much work will be needed to double her speed?
Four times as much, since Kinetic Energy is proportional to V^2.
afsefedrhythyt
To find the work needed to double the speed of the girl, we need to understand the relationship between work and kinetic energy.
Work (W) is defined as the change in kinetic energy (ΔKE) of an object. The kinetic energy of an object is given by the equation KE = 0.5 * m * v^2, where m is the mass of the object and v is its velocity.
In this case, the girl's initial mass is 40 kg, and her initial speed is 1 m/s. To double her speed, her final speed will be 2 m/s.
First, let's calculate the initial kinetic energy (KEi) using the equation KE = 0.5 * m * v^2:
KEi = 0.5 * 40 kg * (1 m/s)^2
= 0.5 * 40 kg * 1 m^2/s^2
= 20 J (Joules)
Next, let's calculate the final kinetic energy (KEf) after doubling her speed:
KEf = 0.5 * 40 kg * (2 m/s)^2
= 0.5 * 40 kg * 4 m^2/s^2
= 80 J (Joules)
To find the work needed to double her speed, we can subtract the initial kinetic energy from the final kinetic energy:
Work = ΔKE = KEf - KEi
= 80 J - 20 J
= 60 J
Therefore, 60 Joules of work will be needed to double the girl's speed.