Waves are observed passing under a dock. Wave crests are 8.0 meters apart. The time for a complete wave to pass by is 4.0 second
1 answer:
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Answer:
v= 14.85 m/s
Explanation:
- When at the bottom of the dip, the only force that keeps the car in the circular trajectory, is the centripetal force.
- This force is not a new force, is just the net force aiming to the center of the circle.
- In this case, is just the difference between the normal force (always perpendicular to the surface, pointing upward) and the force that gravity exerts on the car (which is known as the weight), pointing downward.
- So, we can write the following expression:
- It can be showed that the centripetal force is related to the speed by the following expression:
- The normal force, it is called the apparent weight, because it would be the weight as measured by a scale.
- Replacing (2) in (1), and solving for Fn, we get:
- Now, we need to find the value of v that makes Fn, exactly 15% more than the weight m*g, so we can write the following equation:
- Replacing Fg by its value, simplifying, and solving for v, we get:
Answer:
.
Explanation:
The efficiency of a machine is the percentage of energy input that was turned into useful energy.
The power rating of this lamp is (same as
,) meaning that
of energy is supplied to this lamp every second.
The question states that out of that
of energy input would be turned into heat, which is not useful energy output in this scenario. Assuming that all other forms of energy loss is negligible. The rest of the
of energy supplied to this lamp would be turned into useful energy output.
Thus, every second, this lamp would receive of energy input and would outputs
of useful work. The efficiency of this lamp would be:
.