If the diving board is 3.00 m above the water, what is the diver's speed just before she enters the water?
1 answer:
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The representation of this problem is shown in Figure 1. So our goal is to find the vector 
. From the figure we know that:
From geometry, we know that:
Then using vector decomposition into components:
Therefore:
So if you want to find out <span>how far are you from your starting point you need to know the magnitude of the vector, that is:
</span>
Finally, let's find the <span>compass direction of a line connecting your starting point to your final position. What we are looking for here is an angle that is shown in Figure 2 which is an angle defined with respect to the positive x-axis. Therefore:
</span>
From geometry, we know that:
Then using vector decomposition into components:
Therefore:
So if you want to find out <span>how far are you from your starting point you need to know the magnitude of the vector
</span>
Finally, let's find the <span>compass direction of a line connecting your starting point to your final position. What we are looking for here is an angle that is shown in Figure 2 which is an angle defined with respect to the positive x-axis. Therefore:
</span>
Answer:
The first part can be solved via conservation of energy.
For the second part,
the free body diagram of the car should be as follows:
- weight in the downwards direction
- normal force of the track to the car in the downwards direction
The total force should be equal to the centripetal force by Newton's Second Law.
where because we are looking for the case where the car loses contact.
Now we know the minimum velocity that the car should have. Using the energy conservation found in the first part, we can calculate the minimum height.
Explanation:
The point that might confuse you in this question is the direction of the normal force at the top of the loop.
We usually use the normal force opposite to the weight. However, normal force is the force that the road exerts on us. Imagine that the car goes through the loop very very fast. Its tires will feel a great amount of normal force, if its velocity is quite high. By the same logic, if its velocity is too low, it might not feel a normal force at all, which means losing contact with the track.