Answer:

Explanation:
The index of refraction is equal to the speed of light c in vacuum divided by its speed v in a substance, or
. For our case we want to use
, which for our values is equal to:

Which we will express with 3 significant figures (since a product or quotient must contain the same number of significant figures as the measurement with the <em>least</em> number of significant figures):

By the law of momentum conservation:-
=>m¹u¹ + m²u² = m1v1 + m²v² {let East is +ve}
=>u¹ + u² = v¹ + v² {as m1=m2}
=>3.5 - 2.75 = v1-1.5
<span>
=>v¹ = 2.25 m/s (East) </span>
Answer:
22.5J
Explanation:
Here the force is given. Also, the displacement is given as 30cm.
First we should check if all the values are in their standard form.
Here 30cm should be converted to metre by dividing it with 100.
Which would give us 0.3m
Now we use the equation W=force x displacement =75 x 0.3=22.5J
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