CHAPETR 9 FORCE AND LAWS OF MOTION
VERY SHORT QUESTIONS ( 5 x 5=25)
1. A boy of mass 60 kg running at 3 m/s jumps on to a trolley of mass 140 kg moving with a velocity of 1.5 m/s in the same direction. What is their common velocity?
(m1=60kg,m2=140kg,u1=3m/s,u2=1.5m/s,v=?)
[Formula: m1u1+m2u2= (m1+m2)v]
2. Obtain Expression for law conservation of momentum. 3. A boy of mass 50 kg running at 6 m/s jumps on to a trolley of mass 150 kg moving with a velocity of 10 m/s in the same direction. What is their common velocity?
(m1=50kg,m2=150,u1=6m/s,u2=10m/s,v=?)
[Formula: m1u1+m2u2=(m1+m2)v]
4. There are cars with masses 4kg and 10kg respectively that are at rest car having the mass 10kg moves towards east with the velocity of 5m/s find the velocity of car with mass 4kg with respect to ground.
(m1=4kg,m2=10kg,v1=?,v2=5m/s)
[ Formula m1v1+m2v2=0]
5. Find the velocity of bullet of mass 5gram with fired from a pistol of mass 1.5kg.The recoil velocity is 1.5m/s.
(mb=0.005kg {because kg conversion} ,mp=1,5kg,vb=?,vp=-1.5m/s{negative sign recoil velocity}.)
[ Formula mbvb+mpvp=0].
Answer Key
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