Explain why 15yr old need more calcium than adults
2 answers:
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Answer:
a)
b)
Explanation:
The net force on the car must produce the centripetal acceleration necessary to make this circle, which is . At the top of the circle, the normal force and the weight point downwards (like the centripetal force should), while at the bottom the normal force points upwards (like the centripetal force should) and the weight downwards, so we have (taking the upwards direction as positive):
Which means:
The limit for falling off would be , so the minimum speed would be:
Answer:
2.31J
Explanation:
the energy for a spring system is given by:
where is the spring constant:
and
is the distance stretched from the equilibrium position.
In the first case
so the energy to stretch the spring 1.81cm is:
and for the second case, the energy to stretch the spring 5.79cm:
so to answer a) we must find the difference between these energies:
Answer:
Work done to lift the box is 515.03 J
Explanation:
By work energy theorem we know that work done by all forces is equal to change in kinetic energy
So we have
so we have
so we have