Question

A block of mass 10 kg is released on a fixed wedge inside a cart which is moving with constant velocity 10 $m{s}^{-1}$ towards right. There is no relative motion between block and cart. Then work done by normal reaction on block in two seconds from ground frame will be: $(g=10m{s}^{-2})$

• A. $1320J$
• B. $960J$
• C. $1200J$
• D. $240J$

Answer 1

Answer: (B)

$960J$

$N=mgcos\theta =4mg/5$

Displacement along the wedge for two seconds = 0m

horizontal displacement of cart = 20m

Normal reaction = $4mg/5=80N$ perpendicular to wedge.

Work done by N = $N.(s_1+s_2)$

$N\times s_1=80\times 20\times sin\theta =960$

$N\times s_2=0$

$W_N=960J$