An ambulance moving at 42 m/s sounds its siren whose frequency is 450 hz. a car is moving in the same direction as the ambulance
1 answer:
(a) Since the ambulance and the car are moving one relative to each other, we have to use the general formula of the Doppler effect, which gives us the shift of the frequency of the siren as heard by an observer in the car:
where
f' is the apparent frequency as heard by the observer in the car
v is the velocity of the wave
is the velocity of the observer (positive if it is moving towards the source, negative if it is moving away)
is the velocity of the source (positive if the source is moving away from the observer, negative if is is moving towards it)
f is the real frequency of the sound
In the first part of the problem:
(speed of the sound wave)
(the car is moving away from the ambulance)
(the ambulance is moving towards the car)
(original frequency of the sound)
If we plug the numbers into the formula, we find
b) This time, the ambulance passes the car, so the ambulance is now moving away from the car; this means that must be positive:
Moreover, the car is now moving towards the ambulance, so we should reverse also the sign of:
All the other data do not change, so if we use the same formula as before, we find
where
f' is the apparent frequency as heard by the observer in the car
v is the velocity of the wave
f is the real frequency of the sound
In the first part of the problem:
If we plug the numbers into the formula, we find
b) This time, the ambulance passes the car, so the ambulance is now moving away from the car; this means that
Moreover, the car is now moving towards the ambulance, so we should reverse also the sign of
All the other data do not change, so if we use the same formula as before, we find
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Answer:
The value is
Explanation:
Generally the velocity attained by the sled after t = 3.10 s is mathematically evaluated using the kinematic equation as follows
Here u = 0 \ m/s
a = 13.5
So
=>
The is distance it covers at this time is
=>
=>
Now when sled stops its the final velocity is while the initial velocity will be the velocity after its acceleration i.e
So
Here , the negative sign shows that it is deceleration
So
=>
Explanation:
It is given that,
Magnetic field, B = 0.1 T
Acceleration,
Charge on electron,
Mass of electron,
(a) The force acting on the electron when it is accelerated is, F = ma
The force acting on the electron when it is in magnetic field,
Here,
So,
Where
v is the velocity of the electron
B is the magnetic field
v = 341250 m/s
or
So, the speed of the electron is
(b) In 1 ns, the speed of the electron remains the same as the force is perpendicular to the cross product of velocity and the magnetic field.
Answer:
See the explanation below.
Explanation:
12) When an object is falling, how does the objects velocity change? what formula do you use?
The speed of a falling object is increased by a value of 9.81 meters per second per second. That is if we throw any body regardless of mass from a considerable height, its speed in the first second will be 9.81[ m/ s] , in the next second will be equal to 19.62 [m/s] in the next will be equal to 29.43 [m/ s].
The formula is:
where:
vo = initial velocity = 0
g = gravity = 9.81[m/s^2]
t = time [s]
13)
what is a falling speed at 6s, 9s, 112s?
v = 0 + (9.81*6) = 58.86[m/s]
v = 0 + (9.81*9) = 88.29 [m/s]
v = 0 + (9*112) = 1098.72 [m/s]
14)
If an object is falling at 65 [m/s]. How long has it been falling ? what is the formula that you use?
The formula is the same:
65 = 0 + 9.81*t
t = 65/9.81
t = 6.62[s]
15)
What formula is used to determine the distance an object is falling ?
where:
y = distance [m]
yo = initial distance, in most of the cases and depending of the reference point it will be eqaul to zero
vo = initial velocity, if it is free fall, then = 0
t = time [s]
g = gravity = 9.81[m/s^2]
This equation will be reduce to:
16)
using the times given in problem 13. Determine the distance fallen for each.
y = 0.5*9,81*(6)^2 = 176.58 [m]
y = 0.5*9,81*(9)^2 = 397.3 [m]
y = 0.5*9,81*(112)^2 = 61528.3 [m]
17)
If an object has fallen a distance of 87.3 [m]. How long was it falling?
87.3 = 0.5*9.81*t^2