A 45.0 kg girl is standing on a 159 kg plank. The plank, originally at rest, is free to slide on a frozen lake, which is a flat,
1 answer:
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For the part a) we need only the momentum of the box and we have the data to find it.
Momentum is given by,
where clearly, p is the momentum, m the mass of the box and v is the velocity.
Substituting,
For part b) we need an analysis of the situation. We understand that the box on a surface that has no friction will continue to rotate at the same speed previously defined. The box can only stop with friction, so,
<em>It is the same that part a)</em>
Answer:
The speed with which the skier was going is approximately 2.9906 m/s
Explanation:
The given parameters are;
The distance the skier slides before coming to rest, s = 12.4 m
The coefficient of friction between the skier and the snow, = 0.0368
Therefore, for conservation of energy, we have;
Initial kinetic energy = Work done by the kinetic friction force
Initial kinetic energy = 1/2·m·v²
The work done by the kinetic friction force = ×m×g×s
Where;
m = The mass of the skier
v = The speed with which the skier was going
g = The acceleration due to gravity = 9.8 m/s²
s = The distance the skier slides before coming to rest = 12.4 m
= The kinematic friction = 0.0368
Therefore, for conservation of energy, we have;
1/2·m·v² = ×m×g×s
1/2·v² = ×g×s
v² = 2××g×s = 2 × 0.0368 × 9.8 × 12.4 = 8.943872
v = √(8.943872) ≈ 2.99063070271 ≈ 2.9906 m/s
The speed with which the skier was going = v ≈ 2.9906 m/s.