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# From an automatic gun a man fires 360 bullets per minute with speed of 360 km/hr. If each weighs 20g the power of gun

$(a)\;600\;W \quad (b)\;300\;W \quad (c)\;150\;W \quad (d)\;75\;W$

Power $= \large\frac{W}{t}$, where work done $W = F \times d = m \times a \times d$
360 bullets are fired in one minute $\rightarrow$ time taken for firing 1 bullet $t = \large\frac{60}{360}$ $= \large\frac{1}{6}\;$$s Now, v = u + a t, but u = 0 as the bullet starts from rest and v = 360 km/hr = 100 m/s \Rightarrow 100 = 0 + a \large\frac{1}{6}$$ \rightarrow a = 600 m/s^2$
we can use the kinematic equation $s = ut + \large\frac{1}{2}$$at^2 to calculate the distance. \Rightarrow s = 0 + \large\frac{1}{2}$$ 600\;m/s^2 \times \large (\frac{1}{6})^2$$= \large\frac{25}{3}$$m$