A ball with a mass of $3 k g$ $3 kg$ moving at $8 \frac{m}{s}$ $8 m/s$ hits a still ball with a mass of $4 k g$ $4 kg$ . If the first ball stops moving, how fast is the second ball moving?

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Answer 1 · 2018-07-31T06:35:34

The speed of the second ball is $= 6 m s^{- 1}$ $=6ms^-1$

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

The mass $m_{1} = 3 k g$ $m_1=3kg$

The velocity $u_{1} = 8 m s^{- 1}$ $u_1=8ms^-1$

The mass $m_{2} = 4 k g$ $m_2=4kg$

The velocity $u_{2} = 0 m s^{- 1}$ $u_2=0ms^-1$

The velocity $v_{1} = 0 m s^{- 1}$ $v_1=0ms^-1$

Therefore,

$3 \cdot 8 + 4 \cdot 0 = 3 \cdot 0 + 4 \cdot v_{2}$ $3*8+4*0=3*0+4*v_2$

$v_{2} = \frac{24}{4} = 6 m s^{- 1}$ $v_2=24/4=6ms^-1$

A ball with a mass of 3kg3 kg moving at 8ms8 m/s hits a still ball with a mass of 4kg4 kg. If the first ball stops moving, how fast is the second ball moving?