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>
False the North Star never changes it position
Answer:
Power = 2.45Kw or 2450 Watts.
Explanation:
<u>Given the following data;</u>
Mass, m = 250kg
Height, h = 2m
Time, t = 2secs
We know that acceleration due to gravity, g is equal to 9.8m/s²
Power can be defined as the energy required to do work per unit time.
Mathematically, it is given by the formula;
But Energy = mgh
Substituting into the equation, we have

Power = 2450 Watts
To convert to kilowatt (Kw), we would divide by 1000
Power = 2450/1000
Power = 2.45Kw.
Therefore, the average power output of the weightlifter is 2.45 Kilowatts.