Question

A body completes one round of a circle of radius 'R
in 20 second. The displacement of the body after
45 second is​

Answer 1

Answer:

2$\sqrt{2}$

Explanation:

Every 20 seconds, the body completes one round of the circle.

So the rounds completed in 45 seconds will be 2 because in 40 seconds it can complete 2 rounds.

Now the particle is somewhere near to the starting point.

The body can complete 1/4 of the circle in 5 seconds.

So the displacement will be between a quarter of the circle.

The answer will be 2$\sqrt{r}$

Answer 2

Answer :

√2 R

Given :

• A body completes one round of a circle of radius 'R ' in 20 second

To Find :

• Displacement of the body after 45 seconds

Solution :

We know that , " Displacement of 1 complete round of the circle is zero "

Here ,

A body can completes one complete round in 20 seconds .

So , for two complete rounds , it will takes 40 seconds .

So for both of these cases the displacement would be zero .

Now for remaining 5 seconds it will cover quarter of the circle as shown in attachment . Distance is from point A to point B .

Now displacement is the shortest distance b/w two points. So draw a straight line touching A & B as shown in attachment .

Apply Pythagoras theorem for finding the displacement .

Let the displacement would be " AB "

⇒ AB² = R² + R²

⇒ AB = √(2R²)

⇒ AB = √2 R