A shell of mass 5 kg is fired at 60 degree to the horizontal with a speed of 20 m/sec. Neglecting the air resistance, the K.E of Shell in joule is at highest point is?

a) zero b) 25 c) 1.6 d) 250

1 Answer
A08
Apr 14, 2018

When the shell is fired, it has both horizontal as well as vertical velocity. Both velocities are orthogonal to each other. Therefore these can be treated independently.

At the highest point the vertical component of the velocity #=0#. As such the shell has only the horizontal component of velocity which is given as

#v_"hor"=20\ cos60^@#
#v_"hor"=10\ ms^-1#

Kinetic energy of the shell is due to this component only which is given as

#KE=1/2mv^2#

Inserting various values we get

#KE=1/2xx5xx(10)^2#
#KE=250\ J#

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