Answer:
A)
B) 
Explanation:
A) Using the Archimedes' force we can find the weight of water displaced:

Where:
: is the weight of the block in the air = 20.1 N
: is the weight of the block in the water = 15.3 N

Now, the mass of the water displaced is:

The volume of the block can be found using the mass of water displaced and the density of the water:

B) The density of the block can be found as follows:

I hope it helps you!
<h2>
Answer: Toward the center of the circle.</h2>
This situation is characteristic of the uniform circular motion , in which the movement of a body describes a circumference of a given radius with constant speed.
However, in this movement the velocity has a constant magnitude, but its direction varies continuously.
Let's say
is the velocity vector, whose direction is perpendicular to the radius
of the trajectory, therefore
the acceleration
is directed toward the center of the circumference.
Answer:
Orange , yellow, green and blue
red coat absorbs all colors of visible light except red, so red light
is the only light left to bounce off of the coat toward our eyes.
Efficiency is calculated through dividing the actual mechanical advantage by the hypothetical mechanical advantage:
- the actual mechanical advantage is 9J because that's how much work the light bulb doing
- the hypo. mechanical advantage is 100J. Ideally, in a perfect world, the light bulb can convert 100J input into 100J output, but do to resistance and other factors it is not possible.

change the decimal to a percentage:

the light bulb had 9% efficiency
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