A boy in a wheelchair (total mass, 46.9kg) wins a race with a skateboarder. He has a speed of 1.30m/s at the crest of a slope 2.35m high and 12.6m long. At the bottom of the slope, his speed is 6.28m/s. If air resistance and rolling resistance can be modeled as a constant frictional force of 41.3N, calculate the work he did in pushing forward on his wheels during the downhill ride
energy at crest ... (1/2 m Vc^2) ... Ec
energy at bottom ... (1/2 m Vb^2) ... Eb
Eb = Ec + (m g h) + work - (12.6 * 41.3)
So should I substitute work or calculate Eb?
Then is it work minus 12.6*41.3 or work=12.6*41.3?
Bit confused there. Thank you
https://www.jiskha.com/display.cgi?id=1508888603
you have all the values except the work
that's what the question asks for
work = Eb - Ec - (m g h) + (12.6 * 41.3)
To calculate the work done by the boy in pushing forward on his wheelchair during the downhill ride, we can use the work-energy principle. The work done is equal to the change in kinetic energy.
First, let's calculate the initial kinetic energy of the boy at the crest of the slope. The formula for kinetic energy is:
KE = (1/2) * m * v^2
where KE is the kinetic energy, m is the mass, and v is the velocity.
Given:
Mass of the boy (m) = 46.9 kg
Initial velocity (v) = 1.30 m/s
Calculating the initial kinetic energy:
KE_initial = (1/2) * 46.9 kg * (1.30 m/s)^2
Next, let's calculate the final kinetic energy of the boy at the bottom of the slope. We can use the same formula as above.
Given:
Final velocity (v) = 6.28 m/s
Calculating the final kinetic energy:
KE_final = (1/2) * 46.9 kg * (6.28 m/s)^2
Now, let's find the work done by the boy.
Work = KE_final - KE_initial
Finally, calculate the work by subtracting the initial kinetic energy from the final kinetic energy:
Work = KE_final - KE_initial
Plug in the values for KE_final and KE_initial to calculate the work done by the boy.