Answer:
The spring constant is 60,000 N
The total work done on it during the compression is 3 J
Explanation:
Given;
weight of the girl, W = 600 N
compression of the spring, x = 1 cm = 0.01 m
To determine the spring constant, we apply hook's law;
F = kx
where;
F is applied force or weight on the spring
k is the spring constant
x is the compression of the spring
k = F / x
k = 600 / 0.01
k = 60,000 N
The total work done on the spring = elastic potential energy of the spring, U;
U = ¹/₂kx²
U = ¹/₂(60000)(0.01)²
U = 3 J
Thus, the total work done on it during the compression is 3 J
The apparent velocity is B) 48 m/s north
Explanation:
Here we have a problem of relativity of velocities.
In fact, the train is travelling north at a speed of

where this velocity is measured with respect to the ground.
At the same time, a passenger on the train is walking towards the rear (so, south) at a velocity of

where this velocity is measured with respect to the train, which is in motion in the opposite direction.
Therefore, the apparent velocity of the passenger with respect to an observer standing on the ground is:

And the direction is north, since this number is positive.
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Answer:
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