Please Help. Cant seem to figure out the answers. Please provide explanations fo
ID: 1518043 • Letter: P
Question
Please Help. Cant seem to figure out the answers. Please provide explanations for each answer. Thank you.
1. A glider on a frictionless level air track is moving to the right at a speed of 20cm/s. It collides with a springy rubber-band bumper at the end of the track, and bounces back with a speed of cm/s to the left. if we consider the time interval just before the glider collides with the bumper until just after its no longer in contact with the bumper, which of the following statements is true?
A. A net impulse was imparted to the glider, and some work was done on the glider.
B. A net impulse was imparted to the glider but zero work was done on the glider
C. Zero net impulse was imparted to the glider, but some net work was done on the glider.
D. Zero net impulse was imparted to the glider, and zero net work was done on the glider.
2. Three balls of equal masses are fired simulatneously from a projectile launcher. They are launched with qual speeds from the same height above the ground. Ball 1 is fired straight up, ball 2 is fired horizontally, and ball 3 is fired straight down. Rank in order from largest to smallest, their speeds v1, v2 and v3 just before they hit the ground.
A. v1>v2>v3
B. v1 = v2 = v3
C. v3 > v2 > v1
D. v1 = v3 > v2
E. v2 > v1 = v3
3. A 2kg block sliding at 5m/s on a frictionless surface coillides with a 2kg block at rest. After the collision, one kg block has a velocity of 3m/s and the other 2 kg block has a velocity of 4 m/s. Which statement best describes whether this collision is possible?
A. Even though kinetic energy is not conserved, this collision is possible since momentum is conserved.
B. This collision is possible because both momentum and KE are conserved.
C. Even though KE is conserved, this collision is not possible since momentum is not conserved.
D. This collision is not possible because neither momentum nor KE are conserved.
E. Even though momentum is conserved, this collision is not possible since KE is not conserved.
Explanation / Answer
1)
correct option is (A)
A net impulse was imparted to the glider, and some work was done on the glid
impulse, I=m(v1-v2)
and I=Favg*t
2)
ball 1 fired straight up and v1 is the speed just before hiting the ground
ball 2 fired horizontally with v2 is the speed just before hiting the ground
ball 3 fired straight down with v3 is the speed just before hiting the ground
the correct option (C) is,
V3>v2>v1
3)
let,
m1=2kg, u1=5m/sec, v1=3 m/sec
m2=1 kg, u2=0, v2=4m/sec
use,
initial momentum, P1=m1*u1+m2*u2
P1=2*5+1*0 = 10 kg*m/sec
final momentum, P2=m1*v1+m2*v2
P2=2*3+1*4=10 kg*m/sec
here,
P1=P2 ====> momentum is conserved
initial, K.Ei=1/2*m1*u^2+1/2*m2*u^2
=1/2*2*5^2+1/2*1*0^2=25 J
final K.Ef=1/2*m1*v1^2 + 1/2*m2*v2^2
=1/2*2*3^2 + 1/2*1*4^2 =25 J
therefore, K.Ei=K.Ef ===> K.E is conserved
correct option is (B)
This collision is possible because both momentum and KE are conserved.