Question

1: A standard issue service pistol is the Beretta M9. It fires a 9 mm diameter round that has a massof 8 gr. The standard muzzle velocity is 360 m/s. The barrel is 12.7 cm long. A. How long does the bullet take to travel through the barrel after it is fired? (Hint: ᡴ̅ in t = d/v is the average v of the bullet in the barrel.) B. What is the acceleration of the bullet while it is in the barrel? C. What is the force (N) applied to the bullet to produce this acceleration?

2: Your 1,360 kg car accelerates at 2.5 m/s2 for 4 s. What is the net force applied to produce this acceleration? What is the car's final velocity? ( in mi/hr ) How far does the car move during the acceleration? (in m and ft)

Answer 1

1

A) velocity = 360 m/s

barrel length = 12.7 cm = 0.127 m

time required to travel through barrel = 0.127/360=3.528*10^-4 s

B)

initial velocity = 0

final velocity 360 m/s

distance travelled = 0.127 m

let acceleration be a

360²=0²+(2*a*0.127)

a=510236.22 m/s²

C)Force applied = mass*acceleration = 0.008*510236.22=4081.9 N

2)

mass of car=1360 kg

acceleration=2.5 m/s²

net force applied = mass*acceleration=1360*2.5=3400 N

car's final velocity = acceleration*time = 2.5*4=10 m/s = 22.37 miles/hr

distnace travelled by car in 4 seconds= 0.5*2.5*4²=20 m = 65.6 feet