Answer:
338.16 J
Explanation:
We are given that
Total mass ,m=56 kg
[tex]v_0=1.4 m/s[/tex]
[tex]h=2.3 m[/tex]
[tex]l=12.4 m[/tex]
[tex]v=6.4 m/s[/tex]
Friction force,f=41 N
We have to find the work done by boy in pushing the forward on his wheels during the downhill ride.
According to law of conservation of energy
[tex]\frac{1}{2}mv^2_0+mgh+W=\frac{1}{2}mv^2+W_f[/tex]
[tex]W=\frac{1}{2}mv^2+W_f-\frac{1}{2}mv^2_0-mgh[/tex]
[tex]W=\frac{1}{2}m(v^2-v^2_0)+fl-mgh[/tex]
Where g=[tex]9.8 m/s^2[/tex]
[tex]W=\frac{1}{2}(56)((6.4)^2-(1.4)^2)+41(12.4)-56\times 9.8\times 2.3[/tex]
[tex]W=338.16 J[/tex]
