Answer:
30%
Explanation:
Efficiency = useful work / heat absorbed x 100
= 120/400 x 100
= 0.3 x 100
= 30%
Answer:
Explanation:
the higher up on the Main Sequence the star is, the shorter it lives. The smaller main sequence stars have low luminosities and low surface temperatures. These stars take a very long time to fuse hydrogen into helium and will therefore live a very long life.
We can calculate the length of each spring by using the relationship:

where
F is the force applied to the spring
k is the spring constant
x is the length of the spring (measured with respect to its rest position)
Re-arranging the equation, we have

The force applied to both spring is F=60 N. Spring A has spring constant of k=4 N/m, therefore its length with respect to its rest position is

Spring B has spring constant of k=5 N/m, so its length with respect to its rest position is

Therefore, the correct answer is
<span>
D.Spring A is 3 m longer than spring B because 15 – 12 = 3.</span>