See the graph in attachment
Explanation:
In this problem we have to draw a velocity-time graph for an object travelling initially at -3 m/s, then slowing down and turning around.
In the graph, we see that the initial velocity at time t = 0 is
and it is negative, so below the x-axis.
Later, the object slows down: this means that the magnitude of its velocity increases, therefore (since the velocity is negative) the curve must go upward, approaching and reaching the x-axis (which corresponds to zero velocity).
After that, the object's velocity keep increasing, but now it is positive: this means that the object is travelling in a direction opposite to the initial direction, so it has turned around.
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Answer: 0.4 m
Explanation:
Given
Speed of ambulance, vs = 61.9 m/s
Speed of car = 28.5 m/s
Frequency of ambulance siren, f = 694 Hz
Velocity of sound in air, v = 343 m/s
With speed of ambulance being (61.9 m/s) -> We solve using
fd = f(v + vr) / (v - vs), where vr = 0
fd = 694 * (343 + 0) / (343 - 61.9)
fd = 694 * (343 / 281.1)
fd = 694 * 1.22
fd = 847 Hz
Recall,
λ = v/f
λ = 343/847
λ = 0.4 m
Therefore, the wavelength of the sound of the ambulance’s siren if you are standing at the position of the car is 0.4 m
Water may come into contact with very hot rock heated by magma
Answer:
The final speed at the gree light is 5.714 m/s
Explanation:
Given that,
Initial speed of the motorist (U) = 20m/s
Displacement of the traffic light (S) = 200m
time taken to slam the brake (t₁) = 1s
Now, the displacement of the motorist, till she slams the brake
S₁ = U × t₁
= 20 × 1
= 20m
The remaining distance would be
S₂ = S - S₁
S₂ = 200 - 20
S₂ = 180m
Now, the deceleration of the motorist
S₂ = Ut + 1/2at²
180 = (20 × 14) + 0.5a(14)²
a = - 1.02m/s²
The final speed would be
v = u + at
v = 20 + (- 1.02)(14)
v = 5.714 m/s
The final speed at the gree light is 5.714 m/s
