You are launching a 2-kg potato out of a potato cannon. The cannon is 1.5 m long and is aimed 30 degrees above the horizontal. It exerts a 50 N force on the potato. What is the kinetic energy of the potato as it leaves the muzzle of the potato cannon?

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Answer 1 · 2018-02-01T13:27:18

60 J

MFDocs

The net force on the potato is given by:

$sf(F=50-mgsintheta)$

$:.$ $sf(F=50-2xx9.81xx0.5=40.19color(white)(x)N)$

Using Newton's 2nd Law we get:

$sf(F=ma)$

$:.$ $sf(a=F/m=40.19/2=20.1color(white)(x)"m/s"^2)$

Now we can use the equation of motion:

$sf(v^2=u^2+2as)$

$sf(v^2=0+2xx20.1xx1.5=60.3)$

$sf(v=sqrt(60.3)=7.76color(white)(x)"m/s")$

This is the exit velocity of the potato.

$sf("KE"=1/2mv^2)$

$sf("KE=1/2xx2xx60.3=60.3color(white)(x)J)$