JEE Main 2014 · 12 Apr · Shift 1 · Physics Q4

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PhysicsSingle correct+4 / -1Question 4 of 90

A 4 g bullet is fired horizontally with a speed of 300 m/s into 0.8 kg block of wood at rest on a table. If the coefficient of friction between the block and the table is 0.3, how far will the block slide approximately ?

0.19 m

0.379 m

0.569 m

0.758 m

Answer and worked solution

Official answer: B

Momentum conservation: $v=\dfrac{0.004\times300}{0.804}=1.49$ m/s. Friction decelerates the block at $\mu g=2.94$ m/s², so
$s=\frac{v^2}{2\mu g}=\frac{2.227}{5.88}\approx0.379\text{ m}.$

Topics:Elastic and inelastic collisions Friction

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JEE Main 2014 · 12 Apr · Shift 1, Physics question 4