Q5 is a mixture of SUVAT with momentum/impulse To find the Impulse, the mass, initial and final velocities are required. We already know the mass is 0.2 kg. We can use SUVAT to find the initial and final velocities When the ball is dropped we can find the speed of the ball as it hits the floor the (initial velocity for the impulse) s = 2.5 u = 0 v = ? a = 9.8 t = v^2 = u^2 + 2as gives us v^2 = 0 + 2(9.8)(2.5) v = 7 m/s downward (or technically the initial velocity for the impulse) This speed will change when it hits the ground but we do not know to what value. We can use the greatest height it rebounds to, to work this out (again using suvat) s = 1.8 u = ? v = 0 a = -9.8 (as moving upwards) t = ? v^2 = u^2 + 2as gives us 0 = u^2 + 2(-9.8)(1.8) u^2 = 35.28 u = 5.9397 m/s upwards (or technically the final velocity for the impulse) We now have all the key values to find the impulse I = mv - mu (upwards as the impulse is upwards) I = (0.2)(5.9397) - (0.2)(-7) (7 is negative as it acts downwards) I = 2.59 Ns I hope this makes sense Please let me know if it does not

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