(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

http://u.spig.in/forum/105599049.jpg [Broken]

A projectile is fired at t=0 with velocityv = 20√2 m/sat an angle of 45° degrees as shown. A wall inclined at the same angle and at a distance of40 mstarts moving towards the projectile at the same time (ie., t=0) with a speed of20m/s. Find the time at which the ball collides with the the wall.

2. Relevant equations

General Kinematical Equations

3. The attempt at a solution

I'm getting answer as 2(√3-1) s. Strikingly this is very similar to my friend's answer i.e, 2(√2-1) s. I don't know whose one is correct. Help me.

My Solution,

Let the base of the wall has moved a distance 40-x m at the time the ball collides with the wall. Let the height at which the collision occurs is y.

Then we have,

20t = 40-x ..... (1) (for wall)

y = 20t-5t^{2}...... (2) (for ball)

and x+y=20t ..... (3) (General diagram and since angle is 45 deg)

Solving for ' t ' , a quadratic I got, t = 2(√3-1) s (Other value being negative)

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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# Homework Help: Projectile Problem

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