Flag Mechanics> A girl throws a ball an initial velocity ...
question mark

A girl throws a ball an initial velocity v at an angle of 45∘. The ball strikes a smooth vertical wall at a horizontal distance d from the girl and after rebound returns to her hands. What is the coefficient of restitution between wall and ball? (v2>dg)

ravi , 3 Years ago
Grade 11
anser 1 Answers
Heer Shah

Last Activity: 3 Years ago

Let the wall be d distance away.
When ball will strike the wall its horizontal velocity will be reversed and will become ev (where v is the velocity of ball just before collision) and vertical velocity remains same.
Vx=vcos45
Before collision
Vx=d/t1...........(1)
After collision  
eVx=d/t2........(2)
 
Vy=vsin45
Now net displacement in y =0 so
0=vy(t1+t2)-0.5g(t1+t2)².......(3)
 
From eqn 1&2:  t1+t2 =d/Vx +d/eVx
From eqn 3:  t1+t2=2Vy/g
 
d/Vx (1+1/e)=2Vy/g
(1+1/e)=2×vsin45×vcos45/dg
1+1/e =v²/dg
1/e =(v²-dg)/dg
e=dg/(v²-dg)

Provide a better Answer & Earn Cool Goodies

Enter text here...
star
LIVE ONLINE CLASSES

Prepraring for the competition made easy just by live online class.

tv

Full Live Access

material

Study Material

removal

Live Doubts Solving

assignment

Daily Class Assignments


Ask a Doubt

Get your questions answered by the expert for free

Enter text here...