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givi [52]
3 years ago
7

A motorist is traveling at 20 m/s. He is 60 m from a stoplight when he sees it turn yellow. Is reaction time, before stepping on

the brake, is 0.50 s. What steady acceleration (slowing down) while braking will bring him to a stop right at the light?
Physics
1 answer:
Gnesinka [82]3 years ago
5 0
V₀ = V₁ + 2ax
V₀ = final velocity which is 0 m/s
V₁ = initial velocity which is 20 m/s
x = distance which is 60-(0.5 x 20) =50m
     this is because his reaction time is 0.5 sec so he traveled 10m before stepping on the break paddle.

a= (V₀-V₁) / 2x
  = (0-20) / 2*50
  = -0.2m/s
the negative is because it is a deceleration speed hence it is 0.2m/s
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A compact disc (CD) is played by a cd player, which uses a laser to read the tracks on the disc. The disc spins initially at app
uranmaximum [27]

Answer:

a. The laser tracking mechanism experiences a changing tangential velocity

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d. The laser tracking mechanism experiences a non-zero tangential acceleration

Explanation:

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This is because the tangential velocity v = rω where r = radius of disc and ω  = angular speed of discs. Since r is constant, v ∝ ω.

Since the angular speed changes from 200 rpm to 500 rpm, thus, the tangential velocity would also change.

So, the laser tracking mechanism experiences a changing tangential velocity

c. The laser tracking mechanism experiences a non-zero angular acceleration

Since angular acceleration, α = Δω/Δt where Δω = change in angular speed and Δt = change in time.

Since there is a change in angular speed from 200 rpm to 500 rpm in time Δt, there is thus a non-zero angular acceleration.

So, The laser tracking mechanism experiences a non-zero angular acceleration

d. The laser tracking mechanism experiences a non-zero tangential acceleration

Since tangential acceleration, a = rα where r = radius of disc and α = angular acceleration.

Since there is an angular acceleration of the disc, there is thus going to be a tangential acceleration given by a = rα.

So, the laser tracking mechanism experiences a non-zero tangential acceleration

Statement b is false because, the disc experiences a changing angular speed from 200 rpm to 500 rpm.

4 0
2 years ago
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Stolb23 [73]

Answer:

Length of pipe organ(L) = 0647 m (Approx)

Explanation:

Given:

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Fundamental frequency (F) = 262 Hz

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Find:

Length of pipe organ(L)

Computation:

Speed of sound (v) = 331 + 0.60(14) m/s

Speed of sound (v) = 339.4

Length of pipe organ(L) = Speed of sound (v) / 2(Fundamental frequency)

Length of pipe organ(L) = 339.4 / 2 (262)

Length of pipe organ(L) = 0647 m (Approx)

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