A force of 25N acts on a body at rest for 0.2s and a force of 70N act for next 0.1s in opposite direction. If the final velocity of the body is 5m/s the mass of the body is?

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A 20 kg wagon originally at rest, is pushed with a force of 7 N for 1.5 s, then with a force of 5 N for 1.7 s and then with a force of 10 N for 3 s. Find the final velocity of the cart.

The correct option is A 2.45 m/sWe know that Impulse = Force × time Total Impulse =F1t1+F2t2+F3t3 =7×1.5+5×1.7+10×3=49 kg m/s Now, change in momentum = Total impulse ⇒20 kg×(v−0)=49 kg m/s v=2.45 m/s

A $20 kg$ wagon originally at rest, is pushed with a force of $7 N$ for $1.5 s$ , then with a force of $5 N$ for $1.7 s$ and then with a force of $10 N$ for $3 s$ . Find the final velocity of the cart.

The correct option is A $2.45 m/s$
We know that
Impulse = Force $\times$ time
Total Impulse $= F_{1} t_{1} + F_{2} t_{2} + F_{3} t_{3}$
$= 7 \times 1.5 + 5 \times 1.7 + 10 \times 3 = 49 kg m/s$
Now, change in momentum = Total impulse
$\Rightarrow 20 kg \times (v - 0) = 49 kg m/s$
$v = 2.45 m/s$