How do you find the force needed to accelerate a 0.007 kg pellet from rest to 125 m/s over a distance of 0.8 m along the barrel?

Question

6121 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2018-03-24T13:43:10

The force is $=68.36N$

Apply the equation of motion

$v^2=u^2+2as$

The initial velocity is $u=0ms^-1$

The final velocity is $v=125ms^-1$

The distance is $s=0.8m$

$a=(v^2-u^2)/(2s)=(125^2)/(2*0.8)=9765.625ms^-2$

The mass of the pellet is $=0.007kg$

According to Newton's Second Law of Motion

$F=ma$

The force is $F=0.007*9765.625=68.36N$

Answer 2 · 2018-03-24T13:44:56

$F= 68.36 N$

$m=0.007$ $Kg$
$u=0$ $ms^-1$
$v=125$ $ms^-1$
$s=0.8 m$

Applying a motion equation:

$v^2=u^2 + 2as$
$15 625 = 1.6a$
$a= 9765.625$ $ms^-2$

$F = ma$
$F=0.007 * 9765.625$
$F= 68.36 N$

Again, that's valid assuming we have no other forces on the motion axis acted on the object whatsoever.