Question

If a skater of weight 3 kg has initial speed 32 m/s and second one of weight 4 kg has 5 m/s. After collision, they have speed (couple) 5 m/s. Then the loss in K.E. is

• A. 48 J
• B. 96 J
• C. Zero
• D. None of these

Answer 1

Answer: (D)

None of these

Answer 2

Loss in K.E. = (initial K.E. – Final K.E.) of

system

$\frac { 1 } { 2 } m _ { 1 } u _ { 1 } ^ { 2 } + \frac { 1 } { 2 } m _ { 2 } u _ { 2 } ^ { 2 } - \frac { 1 } { 2 } \left( m _ { 1 } + m _ { 2 } \right) V ^ { 2 }$

$= \frac { 1 } { 2 } 3 \times ( 32 ) ^ { 2 } + \frac { 1 } { 2 } \times 4 \times ( 5 ) ^ { 2 } - \frac { 1 } { 2 } \times ( 3 + 4 ) \times ( 5 ) ^ { 2 }$= 986.5 J