The figure below shows a bullet of mass 190 g traveling horizontally towards the
ID: 778847 • Letter: T
Question
The figure below shows a bullet of mass 190 g traveling horizontally towards the east with speed 415 m/s, which strikes a block of mass 8.0 kg that is initially at rest on a frictionless table.
What are the magnitude (in m/s) and direction of the velocity of the block/bullet combination immediately after the impact?
magnitude (in m/s)
direction: (north, south, east, west, up, down, zero)?
(b)
What are the magnitude (in N · s) and direction of the impulse by the block on the bullet?
magnitude (in N · s)
direction: (north, south, east, west, up, down, zero)?
(c)
What are the magnitude (in N · s) and direction of the impulse from the bullet on the block?
magnitude (in N · s)
direction: (north, south, east, west, up, down, zero)?
(d)
If it took 3 ms for the bullet to change the speed from 415 m/s to the final speed after impact, what is the average force (in N) between the block and the bullet during this time? (Enter the magnitude in N.)
Explanation / Answer
m1(bullet) = 190 g = 0.19 kg m2(block) = 8 kg
before collision
speed of bullet v1i = 415 m/s
speed of blovk v2i = 0
momentum before collision Pi = m1*v1i + m2*v2i
after collision
the block and bullet combines
speed of bullet + block = vf
momentum after collision Pf = (m1+m2)*vf
from momentum conservation
total momentum is conserved
momentum before collision = momentum after collision
Pi = Pf
(0.19*415) + 0 = (0.19 + 8)*vf
vf = 9.627 m/s
direction east
====================================
(b)
the magnitude of the impulse by the block on the bullet = m1*vf - m1*v1i
the magnitude of the impulse by the block on the bullet = 0.19*9.627 - 0.19*415 = -77.02 N s
direction = West
(c)
the magnitude of the impulse from the bullet on the block = m2*vf - m2*v2i = 8*9.627 = 77.02 Ns
direction East
-----------------------
(d)
average force = impulse*time = 77.02*3*10^-3 = 0.231 N
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.