Answer question no. 10.

D e a r S t u d e n t, G i v e n, u = 1.2 m / s, v = - 1.2 m / s (o p p o s i t e d i r e c t i o n) t = 1 m s = 10^{- 3} s, m = 100 g = . 1 k g M o m e n t u m b e f o r e c o l l i s i o n, P_{1} = m u = . 1 \times 1.2 = 0.12 k g m / s . M o m e n t u m a f t e r c o l l i s i o n, P_{2} = m v = . 1 \times - 1.2 = - 0.12 k g m / s . C h a n g e i n m o m e n t u m / i m p u l s e i s, P = P_{1} - P_{2} = 0.12 - - 0.12 = 0.24 k g m / s F o r c e i s, F = \frac{C h a n g e i n m o m e n t u m / i m p u l s e}{t i m e} = \frac{0.24}{10^{- 3}} = 240 N R e g a r d s . . . .