Answer:
2.98 second
Explanation:
The severity index is defined by :
a is dimensionless constant that equals the number of multiples of g
Conditions are given as :
Initial velocity, u = 0
Acceleration, a = 34 m/s²
Final velocity, v = 16.4 km/h = 4.56 m/s
We can find t from the above data as follows :
As a is the acceleration that is multiple of g.
So,
So,
Severity index,
Hence, the severity index for the collision is 2.98 seconds.
Answer:
Explanation:
As it’s difficult to catch it from up.
Gravitational force will pull us when we jump.
If gravity was not there, he could catch the ball. But he will float in the sky after that.
That’s the answer
Answer:
0.83 m or 5.57 m
Explanation:
Destructive interference will occur when the distances from the speakers differ by 1/2 wavelength.
The length of 1 cycle of 72.4 Hz is ...
λ = v/f = (343 m/s)/(72.4 Hz) ≈ 4.738 m
So, the distance of the listener from speaker B is ...
3.2 m ± (4.738 m)/2 = {0.83 m, 5.57 m} . . . either of these distances
_____
The location could be at additional multiples of 4.738 m, but we think not. The sound intensity drops off with the square of the distance from the speaker, so identical sound waves from the speakers will sound quite different at different distances from the speakers. For best interference, the distances need to be as close to the same as possible. That will be at 3.2 m and 5.57 m.
_____
<em>Comment on the speed of sound</em>
We don't know what speed you are to use for the speed of sound. We have used 343 m/s. Some sources use 340 m/s, which will give a result different by 2 or 3 cm.
Answer:
the wavelength λ of the light when it is traveling in air = 560 nm
the smallest thickness t of the air film = 140 nm
Explanation:
From the question; the path difference is Δx = 2t (since the condition of the phase difference in the maxima and minima gets interchanged)
Now for constructive interference;
Δx= 
replacing ;
Δx = 2t ; we have:
2t =
Given that thickness t = 700 nm
Then
2× 700 = --- equation (1)
For thickness t = 980 nm that is next to constructive interference
2× 980 = ----- equation (2)
Equating the difference of equation (2) and equation (1); we have:'
λ = (2 × 980) - ( 2× 700 )
λ = 1960 - 1400
λ = 560 nm
Thus; the wavelength λ of the light when it is traveling in air = 560 nm
b)
For the smallest thickness 
∴ 
Thus, the smallest thickness t of the air film = 140 nm
Answer: 6.48m/s
Explanation:
First, we know that Impulse = change in momentum
Initial velocity, u = 19.8m/s
Let,
Velocity after first collision = x m/s
Velocity after second collision = y m/s
Also, we know that
Impulse = m(v - u). But then, the question said, the guard rail delivered a "resistive" impulse. Thus, our impulse would be m(u - v).
5700 = 1500(19.8 - x)
5700 = 29700 - 1500x
1500x = 29700 - 5700
1500x = 24000
x = 24000/1500
x = 16m/s
Also, at the second guard rail. impulse = ft, so that
Impulse = 79000 * 0.12
Impulse = 9480
This makes us have
Impulse = m(x - y)
9480 = 1500(16 -y)
9480 = 24000 - 1500y
1500y = 24000 - 9480
1500y = 14520
y = 14520 / 1500
y = 9.68
Then, the velocity decreases by 3.2, so that the final velocity of the car is
9.68 - 3.2 = 6.48m/s
