An air gun with a 30-cm long barrel fires a 56-g ball straight upwards. While the ball is in the barrel, compressed air exerts a constant force of 3.2-N force upwards. Calculate the maximum height above the end of the air gun that the ball reaches. [Note: The pressure from the air gun is not air resistance; consider it to be a pushing force of sorts.]
(And it must be solved using forces and kinematics, not energy)

Respuesta :

The maximum height of the ball is 1.45 m

While in the barrel, the two forces acting on the ball are its weight W = mg and the force due to compressed air, F.

While in the barrel, the net force acting on the ball is F' = F - mg.

Since the compressed air exerts a force F = 3.2 N on the ball and its mass, m = 56 g = 0.056 kg and g = acceleration due to gravity = 9.8 m/s².

So, F' = F - mg

= 3.2 N - 0.056 kg × 9.8 m/s²

= 3.2 N - 0.5488 N

= 2.6512 N.

We now find the acceleration of the ball in the barrel, a from F' = ma

a = F'/m

= 2.6512 N/0.056 kg

= 47.34 m/s²

We now need to find the velocity with which the ball leaves the barrel from v² = u² + 2as where u = initial velocity of ball = 0 m/s, a = acceleration of ball = 47.34 m/s² and s = length of barrel = 30 cm = 0.30 m

So, substituting the values of the variables into the equation, we have

v² = u² + 2as

v² = (0 m/s)² + 2 × 47.34 m/s² × 0.30 m

v² = 0 m²/s² + 28.404 m²/s²

v² = 28.404 m²/s²

v = √28.404 m²/s²

v = 5.33 m/s

Finally, we find the maximum height the ball reaches after leaving the barrel from

v'² = v² - 2gh where v = initial velocity of ball after leaving the barrel = 5.33 m/s, v' = final velocity of ball at maximum height = 0 m/s (since it is momentarily at rest at maximum height),g = acceleration of ball = acceleration due to gravity = 9.8 m/s² and h = maximum height of ball.

Since we require h, we make h subject of the formula.

So, h = -(v'² - v²)/2g

Substituting the values of the variables into the equation, we have

h = -(v'² - v²)/2g

h = -((0 m/s)² - (5.33 m/s)²)/2(9.8 m/s²)

h = -((0 m²/s² - 28.41 m²/s²)/19.6m/s²)

h = -(- 28.41 m²/s²)/19.6m/s²)

h = 28.41 m²/s²)/19.6m/s²)

h = 1.45 m

So, the maximum height of the ball is 1.45 m

Learn more about maximum height of a ball here:

https://brainly.com/question/14380696

ACCESS MORE