Question

You are letting 540 g of silly putty fall from rest from your dorm room window located 35.0 m above ground level. Your friend in the dorm across the street is observing the situation and throws a 270 g baseball from his window trying to hit your piece of silly putty. His throw is formidable and hits the silly putty right when it is halfway to the ground, and when the baseball is moving horizontally at 15.0 m/s. Baseball and silly putty stick together. Right after the collision, find:

(a) the horizontal and vertical components of the velocity of the two-object system.

(b) their speed and the angle their velocity makes with the horizontal.

Answer 1

The sillly putty mass Mp = 540 g ,

the silly putty  was initailly at rest u = 0 m/s , accln down = g = 9.8 m/s2

it displaces d= 35/2 = 17.5 m

so final velocity before hit is

putting the value we get v = 18.5 m/s downwards

the base ball of mass Mb = 270g = 0.27 kg , velocity of baseball is Vb = 15m/s horizontal

a) using the conservation of momentum

Mp.V (in Y dirn) + Mb.Vb (In X dirn ) = (Mb +Mp).Vf

now in Y coordinate

MpV = (Mb +Mp).Vfy

putting the values we get

Vfy = 12.33 m/s downwards   

now in X coordinate

Mb Vb = (Mb +Mp).Vfx

putting the values we get

Vfx = 5 m/s downwards   

b) the speed is Vf

putting the value we get 13.30 m/s

the angle

we get with the horizontal