A ball with a mass of $13 k g$ $13 kg$ moving at $7 \frac{m}{s}$ $7 m/s$ hits a still ball with a mass of $15 k g$ $15 kg$ . If the first ball stops moving, how fast is the second ball moving?

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Answer 1 · 2018-03-16T10:00:24

The velocity of the second ball is $= 6.07 m s^{- 1}$ $=6.07ms^-1$

$m_{1} u_{1} + m_{2} u_{2} = m_{1} v_{1} + m_{2} v_{2}$ $m_1u_1+m_2u_2=m_1v_1+m_2v_2$

The mass the first ball is $m_{1} = 13 k g$ $m_1=13kg$

The velocity of the first ball before the collision is $u_{1} = 7 m s^{- 1}$ $u_1=7ms^-1$

The mass of the second ball is $m_{2} = 15 k g$ $m_2=15kg$

The velocity of the second ball before the collision is $u_{2} = 0 m s^{- 1}$ $u_2=0ms^-1$

The velocity of the first ball after the collision is $v_{1} = 0 m s^{- 1}$ $v_1=0ms^-1$

Therefore,

$13 \cdot 7 + 15 \cdot 0 = 13 \cdot 0 + 15 \cdot v_{2}$ $13*7+15*0=13*0+15*v_2$

$15 v_{2} = 91$ $15v_2=91$

$v_{2} = \frac{91}{15} = 6.07 m s^{- 1}$ $v_2=91/15=6.07ms^-1$

The velocity of the second ball after the collision is $v_{2} = 6.07 m s^{- 1}$ $v_2=6.07ms^-1$

A ball with a mass of 13kg13 kg moving at 7ms7 m/s hits a still ball with a mass of 15kg15 kg. If the first ball stops moving, how fast is the second ball moving?