A 11,000-kg train car moving due east at 21.0 m/s collides with and couples to a 23,000-kg train car that is initially at rest.
1 answer:
Answer:
v = 6.79 m/s
Explanation:
It is given that,
Mass of a train car, m₁ = 11000 kg
Speed of train car, u₁ = 21 m/s
Mass of other train car, m₂ = 23000 kg
Initially, the other train car is at rest, u₂ = 0
It is a case based on inelastic collision as both car couples each other after the collision. The law of conservation of momentum satisied here. So,
V is the common velocity after the collisions
So, the two car train will move with a common velocity of 6.79 m/s.
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Answer:
The distance from the base of the building to the landing site is 154 m.
The total flight time is 3.5 s.
At the moment of impact, the velocity vector of the cat is v = (44 m/s, -34.3 m/s) and its magnitude is 55.8 m/s.
Explanation:
The equations for the position and velocity vectors of the cat are as follows:
r = (x0 + v0x · t, y0 + v0y · t + 1/2 · g · t²)
v = (v0x, v0y + g · t)
Where:
r = position vector of the cat at time t.
x0 = initial horizontal position.
v0x = initial horizontal velocity.
t = time.
y0 = initial vertical position.
v0y = initial vertical velocity
g = acceleration due to gravity (-9.8 m/s² considering the upward position as positive).
v = velocity vector of the cat at time t.
Please, see the attached figure for a better understanding of the problem. Notice that the origin of the frame of reference is located at the launching point so that x0 and y0 = 0. In a horizontal launch, initially there is no vertical velocity, then, v0y = 0.
When the cat reaches the ground, the position vector of the cat will be r1 (see figure). The vertical component of r1 is -60 m and the horizontal component will be the horizontal distance traveled by the cat (r1x). Then, using the equation of the y-component of the position vector, we can obtain the time of flight and with that time we can obtain the horizontal distance traveled by the cat:
r1y = y0 + v0y · t + 1/2 · g · t²
-60 m = 0 m + 0 m/s · t - 1/2 · 9.8 m/s² · t²
- 60 m = -4.9 m/s² · t²
-60 m / - 4.9 m/s² = t²
t = 3.5 s
The cat reaches the ground in 3.5 s
Now, we can calculate the horizontal component of r1:
r1x = x0 + v0 · t
r1x = 0 m + 44 m/s · 3.5 s
r1x = 154 m
The distance from the base of the building to the landing site is 154 m.
The total flight time was already calculated and is 3.5 s.
The velocity vector of the cat when it reaches the ground will be:
v = (v0x, v0y + g · t)
v = (44 m/s, 0 m/s - 9.8 m/s² · 3.5 s)
v = (44 m/s, -34.3 m/s)
The magintude of the vector "v" is calculated as follows:
At the moment of impact, the velocity vector of the cat is v = (44 m/s, -34.3 m/s) and its magnitude is 55.8 m/s.
Answer:
r₂ = 0.316 m
Explanation:
The sound level is expressed in decibels, therefore let's find the intensity for the new location
β = 10 log
let's write this expression for our case
β₁ = 10 log \frac{I_1}{I_o}
β₂ = 10 log \frac{I_2}{I_o}
β₂ -β₁ = 10 ( )
β₂ - β₁ = 10
log \frac{I_2}{I_1} = = 3
= 10³
I₂ = 10³ I₁
having the relationship between the intensities, we can use the definition of intensity which is the power per unit area
I = P / A
P = I A
the area is of a sphere
A = 4π r²
the power of the sound does not change, so we can write it for the two points
P = I₁ A₁ = I₂ A₂
I₁ r₁² = I₂ r₂²
we substitute the ratio of intensities
I₁ r₁² = (10³ I₁ ) r₂²
r₁² = 10³ r₂²
r₂ = r₁ / √10³
we calculate
r₂ =
r₂ = 0.316 m