Answer:
The rate of change of the shadow length of a person is 2.692 ft/s
Solution:
As per the question:
Height of a person, H = 20 ft
Height of a person, h = 7 ft
Rate = 5 ft/s
Now,
From Fig.1:
b = person's distance from the lamp post
a = shadow length
Also, from the similarity of the triangles, we can write:
Differentiating the above eqn w.r.t t:
Now, we know that:
Rate =
Thus
Answer: 90 kgm/s
Explanation:
The momentum (linear momentum) is given by the following equation:
Where:
is the mass of the skater
is the velocity
In this situation the skater has two values of momentum:
Initial momentum:
Final momentum:
Where:
So, if we want to calculate the difference in the magnitude of the skater's momentum, we have to write the following equation(assuming the mass of the skater remains constant):
Finally: