The work done to pull the sister back on the swing is equal to the increase in potential energy of the sister:
(1)
where m is the sister's mass, g is the gravitational acceleration and
is the increase in altitude of the sister with respect to its initial position.
By calling
the angle of the chain with respect to the vertical, the increase in altitude is given by
(2)
where L is the length of the chain.
Putting (2) inside (1), we find
from which we can find the mass of the sister:
Answer:
Angle of incidence = 20°
Angle of reflection = 20°
Explanation:
Applying,
The first Law of Refraction: The incident ray, the reflected ray and the normal at the point of incidence all lies in the plane.
From the diagram,
Angle of incidence = 90-70
Angle of incidence = 20°
From the law of reflection,
Angle of incidence = Angle of reflection
Therefore,
Angle of reflection = 20°
Answer:
The speed with which the man flies forward is 5.5 m/s
Explanation:
The mass of the man = 100 kg
The mass of the scooter = 10 kg
The speed with which the man was traveling on the scooter = 5 m/s
The speed of the scooter after it hits the rock = 0 m/s
Let v represent the speed with which the man flies forward
The formula for momentum, P, is P = Mass × Velocity
The conservation of linear momentum principle is, the total initial momentum = The total final momentum, therefore, we have;
The total initial momentum = (100 kg + 10 kg) × 5 m/s = 550 kg·m/s
The total final momentum = 100 kg × v + 10 kg × 0 m/s = 100 kg × v
When the momentum is conserved, we have;
550 kg·m/s = 100 kg × v
∴ v = 550 kg·m/s/(100 kg) = 5.5 m/s.
The speed with which the man flies forward = v = 5.5 m/s
B.) <span>The amp is the unit for "Current"
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