Marble C, mass 5.0 g, moves at a speed of 20.5 cm/s. It collides with a second marble, D, with mass 10.0 g, moving at 12.0 cm/s in the same direction. After the collision, marble C continues with a speed of 8.0 cm/s in the same direction.
(b) Calculate the marbles' momenta before the collision.
answer in kg · m/s (marble C)
answer in kg · m/s (marble D)
(c) Calculate the momentum of marble C after the collision.
answer in kg · m/s
(d) Calculate the momentum of marble D after the collision.
answer in kg · m/s
(e) What is the speed of marble D after the collision?
answer in cm/s
A 2560-kg van runs into the back of a 820-kg compact car at rest. They move off together at 8.5 m/s. Assuming the friction with the road is negligible, calculate the initial speed of the van.
answer in m/s
A 0.201-kg plastic ball moves with a velocity of 0.30 m/s. It collides with a second plastic ball of mass 0.101 kg, which is moving along the same line at a speed of 0.10 m/s. After the collision, both balls continue moving in the same, original direction. The speed of the 0.101-kg ball is 0.26 m/s. What is the new velocity of the 0.201-kg ball?
answer in m/s (in the original direction)
physics help?
2018-01-10 12:17 am
回答 (1)
2018-01-10 1:36 am
1.
1: marble C, 2: marble D
Masses: m₁ = 5.0 g = 0.005 kg, m₂ = 10.0 g = 0.01 kg
Initial velocities: u₁ = 20.5 cm/s = 0.205 m/s, u₂ = 12.0 cm/s = 0.12 m/s
Final velocities, v₁ = 8.0 cm/s = 0.08 m/s, v₂ = ? m/s
(b)
Momentum of marble C before collision = m₁u₁ = 0.005 × 0.205 = 0.00103 kg•m/s
Momentum of marble D before collision = m₂u₂ = 0.01 × 0.12 = 0.0012 kg•m/s
(c)
Momentum of marble C after collision = m₁v₁ = 0.005 × 0.08 = 0.0004 kg•m/s
(d)
Conservation of momentum :
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
0.00103 + 0.0012 = 0.0004 + m₂v₂
Momentum of marble D after collision, m₂v₂ = 0.00183 kg•m/s
(e)
0.01v₂ = 0.00183
Speed of marble D after collision, v₂ = 0.183 m/s = 18.3 cm/s
====
2.
1: the van, 2: the compact car
Masses: m₁ = 2560 kg, m₂ = 820 kg
Initial velocities: u₁ = ? m/s, u₂ = 0 m/s
Final velocities, v₁ = v₂ = 8.5 m/s
Conservation of momentum :
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
2560u₁ + 820*0 = (2560 + 820)*8.5
2560u₁ = 3380*8.5
Initial speed of the van = 11.2 m/s
====
3.
1: the first plastic ball, 2: the second plastic ball
Masses: m₁ = 0.201 kg, m₂ = 0.101 kg
Initial velocities: u₁ = 0.30 m/s, u₂ = 0.10 m/s
Final velocities, v₁ = ? m/s. v₂ = 0.26 m/s
Conservation of momentum :
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
0.201*0.30 + 0.101*0.10 = 0.201v₁ + 0.101*0.26
0.201v₁ = 0.201*0.30 + 0.101*0.10 - 0.101*0.26
New velocity of the 0.201-kg ball, v₁ = 0.22 m/s
1: marble C, 2: marble D
Masses: m₁ = 5.0 g = 0.005 kg, m₂ = 10.0 g = 0.01 kg
Initial velocities: u₁ = 20.5 cm/s = 0.205 m/s, u₂ = 12.0 cm/s = 0.12 m/s
Final velocities, v₁ = 8.0 cm/s = 0.08 m/s, v₂ = ? m/s
(b)
Momentum of marble C before collision = m₁u₁ = 0.005 × 0.205 = 0.00103 kg•m/s
Momentum of marble D before collision = m₂u₂ = 0.01 × 0.12 = 0.0012 kg•m/s
(c)
Momentum of marble C after collision = m₁v₁ = 0.005 × 0.08 = 0.0004 kg•m/s
(d)
Conservation of momentum :
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
0.00103 + 0.0012 = 0.0004 + m₂v₂
Momentum of marble D after collision, m₂v₂ = 0.00183 kg•m/s
(e)
0.01v₂ = 0.00183
Speed of marble D after collision, v₂ = 0.183 m/s = 18.3 cm/s
====
2.
1: the van, 2: the compact car
Masses: m₁ = 2560 kg, m₂ = 820 kg
Initial velocities: u₁ = ? m/s, u₂ = 0 m/s
Final velocities, v₁ = v₂ = 8.5 m/s
Conservation of momentum :
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
2560u₁ + 820*0 = (2560 + 820)*8.5
2560u₁ = 3380*8.5
Initial speed of the van = 11.2 m/s
====
3.
1: the first plastic ball, 2: the second plastic ball
Masses: m₁ = 0.201 kg, m₂ = 0.101 kg
Initial velocities: u₁ = 0.30 m/s, u₂ = 0.10 m/s
Final velocities, v₁ = ? m/s. v₂ = 0.26 m/s
Conservation of momentum :
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
0.201*0.30 + 0.101*0.10 = 0.201v₁ + 0.101*0.26
0.201v₁ = 0.201*0.30 + 0.101*0.10 - 0.101*0.26
New velocity of the 0.201-kg ball, v₁ = 0.22 m/s
收錄日期: 2021-04-24 00:52:53
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20180109161746AAaBL1W