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julia-pushkina [17]
2 years ago
8

You are driving downhill on a rural road with a 3% grade at a speed of 45 mph. While playing on the side of the road, a child ac

cidentally runs onto the roadway to pick up a ball. At what distance you must first see the child to stop your vehicle before reaching the child? How would this distance be different if you were driving on the same road and at the same speed, but going uphill? Use t
Physics
1 answer:
Dennis_Churaev [7]2 years ago
5 0

Answer: a) 95.07m b) 81.88 m

Explanation:

a)

For finding the distance when vehicle is going downhill we have the formula as:

Stop sight distance= Velocity*Reaction time + Velocity² / 2*g*(f constant- Grade value)

Now by AASHTO, we have for v= 45 mph= 72.4 kph, f= 0.31

Reaction time= 0.28

So putting values we get

Stop sight distance= 0.28*72.4 *1  + \frac{(0.28*72.4)^{2} }{2*9.81*(0.31-0.03)}

Stop sight distance= 95.07 m

b)

For finding the distance when vehicle is going uphill we have the formula as:

Stop sight distance= Velocity*Reaction time + Velocity² / 2*g*(f constant- Grade value)

Now by AASHTO, we have for v= 45 mph= 72.4 kph, f= 0.31

Reaction time= 0.28

So putting values we get

Stop sight distance= 0.28*72.4 *1  + \frac{(0.28*72.4)^{2} }{2*9.81*(0.31+0.03)}

Stop sight distance= 81.88 m

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Answer:

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Explanation:

For this case we must use Newton's second law,

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bold indicate vectors, so we will write it in its components x and y

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       Fₓ = maₓ

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      Fy - W = m aa_{y}

Now let's examine our case, with indicate that the bird is level, the force of the wings can have a measured angle with respect to the x axis, where the vertical component is responsible for the lift, let's use trigonometry to find the components

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      F sin θ -w = m a

 

As the bird indicates that leveling at the same height, so the vertical acceleration is zero (ay = 0)

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The maximum value of this equation occurs when the sin=1, in this case

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3 0
2 years ago
A satellite revolves around a planet at an altitude equal to the radius of the planet. the force of gravitational interaction be
USPshnik [31]
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A car is moving on a straight road in a fixed direction at a constant speed of v = 62 km/h with respect to the road. You wish to
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Answer:

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