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Standard XII

Physics

1st Equation of Motion

A box of mass...

Question

A box of mass $5$ kg is kept inside a lift. Lift starts from rest and moves upward at a speed of $1 m s^{- 1}$ . What is work done by normal force in first $5 s$ ? $[g = 10 m s^{- 2}]$

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Solution

Normal force $R = m g = 5 \times 10 = 50 N$
Initial speed $u = 1 m / s$
$t = 5 s$
Displacement $S = u t = 1 \times 5 = 5 m$
Work done $W = R \times S = 50 \times 5 = 250 J$

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A box of mass 5kg is kept inside a lift. Lift starts from rest and moves upward at a speed of 1ms−1. What is work done by normal force in first 5s? [g=10ms−2]

Normal force R=mg=5×10=50 NInitial speed u=1 m/st=5 sDisplacement S=ut=1×5=5 mWork done W=R×S=50×5=250 J

A box of mass $5$ kg is kept inside a lift. Lift starts from rest and moves upward at a speed of $1 m s^{- 1}$ . What is work done by normal force in first $5 s$ ? $[g = 10 m s^{- 2}]$

Normal force $R = m g = 5 \times 10 = 50 N$
Initial speed $u = 1 m / s$
$t = 5 s$
Displacement $S = u t = 1 \times 5 = 5 m$
Work done $W = R \times S = 50 \times 5 = 250 J$