Answer: The end point of a spring oscillates with a period of 2.0 s when a block with mass m is attached to it. When this mass is increased by 2.0 kg, the period is found to be 3.0 s. Then the mass m is 0.625kg.
Explanation: To find the answer, we need to know more about the simple harmonic motion.
<h3>
What is simple harmonic motion?</h3>
- A particle is said to execute SHM, if it moves to and fro about the mean position under the action of restoring force.
- We have the equation of time period of a SHM as,

- Where, m is the mass of the body and k is the spring constant.
<h3>How to solve the problem?</h3>

- We have to find the value of m,


Thus, we can conclude that, the mass m will be 0.625kg.
Learn more about simple harmonic motion here:
brainly.com/question/28045110
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To solve this problem we will use the concepts related to Magnification. Magnification is the process of enlarging the apparent size, not physical size, of something. This enlargement is quantified by a calculated number also called "magnification".
The overall magnification of microscope is

Where
N = Near point
l = distance between the object lens and eye lens
= Focal length
= Focal of eyepiece
Given that the minimum distance at which the eye is able to focus is about 25cm we have that N = 25cm
Replacing,


Therefore the correct answer is C.
It will use a lot more energy (electricity) to cool down the room. Because heat energy from outside the room can easily transfer into the room again if the room is not well insulated. So more energy is needed to cool down the room again