Two balls of mass 3kg and 7 kg respectively move towards one another with speeds 5ms^-1 and 2ms^-1 respectively on a smooth table. If they collide and join, what velocity do they move off with?
m = 3kg ; 7kg u = 5ms^-1 ; -2ms^-1 (Taking the direction to the right as positive). momentum before = m1u1 + m2u2 = (3x5) + (7x-2) = 1 momentum after = (m1+m2)v2 = (3+7)v = 10v By the principle of conservation of momentum; momentum before must equal momentum after therefore 1 = 10v. v = 0.1ms^-1. It is positive therefore it moves off towards the right.
AG
Related Physics A Level answers
All answers ▸How does one calculate centripetal force?
A nail of mass 7.0g is held horizontally and is hit by a hammer of mass 0.25kg moving at 10ms^-1. The hammer remains in contact with the nail during and after the blow. (a) What is the velocity of the hammer and nail after contact?
A car of mass m is travelling at a speed v around a circular track of radius r banked at an angle θ. (a) What is the centripetal acceleration of the car? (b) What is the normal force acting on the car? (c) If θ = 45°, r = 1 km what is the maximum speed?
Show that a mass on a spring obeys simple harmonic motion.