Respuesta :
Explanation:
(a) According to the law of conservation of energy,
Potential energy = Kinetic energy
mgh = [tex]\frac{1}{2}mv^{2}[/tex]
Putting the given values into the above formula as follows.
mgh = [tex]\frac{1}{2}mv^{2}[/tex]
[tex]4 \times 9.8 \times h = \frac{1}{2} \times 4 \times (4.2)^{2}[/tex]
h = 0.9 m
Therefore, the height H is 0.9 m.
(b) For the given situation,
Kinetic energy = work done by friction
[tex]\frac{1}{2} \times mv^{2} = \text{friction} \times d[/tex]
[tex]0.5 \times mv^{2} = u \times mg \times d[/tex]
[tex]0.5 \times 4 \times 4.2^{2} = u \times 4 \times 9.8 \times 3[/tex]
u = 0.3
Thus, we can conclude that the coefficient of kinetic friction on the horizontal surface is 0.3.
