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nalin [4]
3 years ago
6

I was driving along at 20 m/s, trying to change a CD and not watching where I was going. When I looked up, I found myself 45 m f

rom a railroad crossing. And wouldn’t you know it, a train moving at 30 m/s was only 60 m from the crossing. In a split second, I realized that the train was going to beat me to the crossing and that I didn’t have enough distance to stop. My only hope was to accelerate enough to cross the tracks before the train arrived. If my reaction time before starting to accelerate was 0.50 s, what minimum acceleration did my car need for me to be here today writing these words?
Physics
1 answer:
cricket20 [7]3 years ago
7 0

Answer:

a=4.44\frac{m}{s^2}

Explanation:

First we have to find the time required for train to travel 60 meters and impact the car, this is an uniform linear motion:

t=\frac{d}{v}\\\\t=\frac{60m}{30\frac{m}{s}}=2s

The reaction time of the driver before starting to accelerate was 0.50 seconds. So, remaining time for driver is 1.5 seconds.

Now, we have to calculate the distance traveled for the driver in this 0.5 seconds before he start to accelerate. Again, is an uniform linear motion:

d=vt\\d=20\frac{m}{s}(0.5s)=10m

The driver cover 10 meters in this 0.5 seconds. So, the remaining distance to be cover in 1.5 seconds by the driver are 35 meters. We calculate the minimum acceleration required by the car in order to cross the tracks before the train arrive, Since this is an uniformly accelerated motion, we use the following equation:

d=v_0t+\frac{1}{2}at^2\\a=\frac{2(d-v_0t)}{t^2}\\a=\frac{2(35m-20\frac{m}{s}*1.5s}{(1.5s)^2}\\a=4.44\frac{m}{s^2}

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1. Two-point charges, QA = +8 μC and QB = -5 μC, are separated by a distance r = 10 cm. What is the magnitude and direction of t
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Explanation:

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We need to find the magnitude and direction of the electric force. It is given by :

F=\dfrac{kq_1q_2}{r^2}\\\\F=\dfrac{9\times 10^9\times 8\times 10^{-6}\times 5\times 10^{-6}}{(0.1)^2}\\\\F=36\ N

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If a clock expends 2 W of power from a 1.5 V battery what amount of current is supplying the clock?
wolverine [178]
1.3 A
If a clock expends 2 W of power from a 1.5 V battery, what amount of current is supplying
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solution
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3 years ago
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Read 2 more answers
Find the angle of depression from the top of a lighthouse 250 feet above water level to the water line of a ship 2.5 miles offsh
Rudik [331]
Height of the lighthouse = 250 feet
Distance of the ship from the shore = 2.5 miles
We already know that
1 mile = 5280 feet
Then
2.5 miles = 5280 * 2.5
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Now, to find the angle of depression, we can use the formula
<span>θ = <span>tan<span>−1 </span></span>(13200/250)
</span>   = 1.50 degrees
I hope that this is the answer that you were looking for and the answer has come to your desired help. 
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