1. Two automobiles of equal mass approach an intersection. One vehicle is travel
ID: 1537059 • Letter: 1
Question
1. Two automobiles of equal mass approach an intersection. One vehicle is traveling with velocity 12.0 m/s toward the east and the other is traveling north with speed v2i. Neither driver sees the other. The vehicles collide in the intersection and stick together, leaving parallel skid marks at an angle of 61.0° north of east. Determine the initial speed v2i of the northward-moving vehicle. m/s
The speed limit for both roads is 35 mi/h and the driver of the northward-moving vehicle claims he was within the speed limit when the collision occurred. Is he telling the truth? Yes/ No
2. A 10.4-g bullet is fired into a stationary block of wood having mass m = 5.02 kg. The bullet imbeds into the block. The speed of the bullet-plus-wood combination immediately after the collision is 0.608 m/s. What was the original speed of the bullet? (Express your answer with four significant figures.)
Please help, thank you
Explanation / Answer
m1 = m2 , v1 =12i m/s, , v = vcos(61) i +vsin(61) j
from conservation of momentum along horizontal direction
m1v1ix +m2v2ix = (m1+m2)vx
12 +0 = 2*vcos(61)
v = 12.38 m/s
from conservation of momentum along vertical direction
m1v1iy +m2v2iy = (m1+m2)vy
0 + v2iy = 2*vsin(61)
v2 = 2*12.38*sin(61)
v2i = 21.66 m/s
u = 35 mi/h = 15.65 m/s
v2i > 15.65 m/s , No , he is not telling truth
2) m1 = 10.4 g, m2 = 5.02 kg
v = 0.68 m/s , u2 = 0
from conservation of momentum
m1u1 +m2u2 = (m1+m2)v
0.0104*u1 +0 = (0.0104+5.02)*0.608
u1 = 294.1 m/s
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