9702---June 2002---qp 2---Q:4 c

[XPFMember]

Assalamoalaikum!!!
Can anybody help me in question 4 physics
Jazak Allah Khair!!

 

[beacon_of_light]

Well consider the direction of velocities, take down as negative and up as positive !

p = m(v-u)
v = 5.3 m/s
u = -5.6m/s
v-u = 5.3 - ( - 5.6) = 5.3 + 5.6
now solve out urself...

 

[XPFMember]

but why is u -5.6..that is the real confusion

 

[beacon_of_light]

velocity is a vector quantity so consider its direction as well. as the ball falls down its velocity is in one direction but as it strikes the plate and rebounces, the velocity's direction changes. since velocity is a vector quantity, we allocate signs to velocity, as it changes direction. and its up2u whether u take velocities in upward direction as negative or positive. this will determine the direction of velocity in downward direction..

hope u get tht!

 

[XPFMember]

Yes Jazak Allah...now i get it