Question

20. A ball is thrown with a velocity of 7root2 m/s at an angle of 45 degree with the
horizontal. It just clears the two vertical poles of height 0.9m each. Find the
separation between the poles.​

Answer 1

19

57898

568 /nm

4686m root 56710mnv

Answer 2

Answer:

The answer to you question is 8m.

Explanation:

First of all,

Let t be the time after which the ball is at the top of the poles.

Vertical velocity = 7√2 Sin 45°

As we have the velocity we need to find the motion.

We will use the second formula ie,

s = ut + 1/2 gt²

Substituting values we get,

0.9 = 7√2 × 1 / √2 × t - 1 / 2 gt²

gt² - 14t + 1.8 = 0

The equation above is in the form ax² + bx + c so it is a quadratic equation. Now if we use the quadratic formula we are going to find the difference between t1 and t2.

t2 - t1 = √b² - 4ac / a

= √ 14² - 4 × g × 1.8

We have found the difference between the two times. So now we will find the horizontal distance or the separation between the poles.

d = u Cosθ × α × ( t2 - t1 )

d = 7 √14² -  4 × g × 1.8

Simplifying even further we get our answer..

d = 8m

Hope it helps