Question

A ball of mass 100 g travelling with a velocity of 100 m/s collides with another ball of mass 400 g moving at 50 m/s in the same direction. If they stick together, calculate:
(i) their common velocity
(ii) loss of enery and hence state the type collision involved.

I had calculated their common velocity of which i got 60m/s.
Please help me (ii)

Answer 1

linear momentum p=mv

lets say m1 =0.1 kg
m2=0.4kg
before collision pi=(m1. u1)+(m2 . u2)
pi=(0.1 . 100) + ( 0.4.50) = 30

when they collide together pf= (m1+m2)vf
since linear momentum is always conserved pi=pf

pf= (m1+m2)vf =pf
(0.1+0.4) vf = 30
vf=60m/s

you are correct

b)
when two objects stick together their collision is a PERFECTLY inelastic collision

you now have to calculate ki and kf
ki-kf=loss of energy

kf = 1/2 . (m1+m2). vf^2
kf = 1/2 . (0.1+0.4). 60^2=900j

ki = 1/2 .m1 . u1^2 + 1/2 m2 . u2^2
ki = (1/2 . 0.1. 100^2 ) + (1/2 . 0.4 . 50^2)=1000J

energy lost = 100 J

Answer 2

wow! it's great! Thank you somuch AMELIA.

But please help me with the meaning of ki and kf

Answer 3

ki is the kinetic energy initial how much energy is there in the system in the form a speed at the beggining of the collision as you know there are two forms of mechanical energy ( kinetic energy and potential ) when the object is moving it has kinetic energy but when it collides some of the kinetic energy transforms into heat and sound thus the speed of the object slows down.When we calculate the Kf we calculate the energy after the collision.Like I said during an Inelastic collision kf is less then ki because there has been lost of energy ( transform into heat and sounds etcc

Answer 4

Meaning of pi and pf

Answer 5

Thanks
for the solving

Answer 6

SswPlease i dont really understand this answer

Answer 7

I dont understand

Answer 8

Thanks for that