I think this is about the 5th or 6th time I've seen this question
submitted to Brainly. So far, nobody has yet given us any of
the rest of the question ... the part that tells us something about
the vectors, so that we have some way to know their magnitudes.
So far, nada.
Explanation:
Efficiency is a way of describing the amount of useful output a process or machine can generate as a percentage of the input required to make it go. In other words, it compares how much energy is used to do work versus how much is lost or wasted to the environment. The more efficient the machine, the less energy wasted.
For example, if a heat engine is able to turn 75 percent of the fuel it receives into motion, while 25 percent is lost as heat in the process, it would be 75 percent efficient. Out of the original 100 percent of the fuel, 75 percent was output as useful work.
the equation:
energy efficiency =useful output energy/total input energy
Answer:
Most likely, it will be harder to get strong magnets to change phase because they have more density.
I believe the last one about the bike is correct.
Answer:
B. 6 cm
Explanation:
First, we calculate the spring constant of a single spring:

where,
k = spring constant of single spring = ?
F = Force Applied = 10 N
Δx = extension = 4 cm = 0.04 m
Therefore,

Now, the equivalent resistance of two springs connected in parallel, as shown in the diagram, will be:

For a load of 30 N, applying Hooke's Law:

Hence, the correct option is:
<u>B. 6 cm</u>