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trapecia [35]
3 years ago
15

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 46 m

from a railroad crossing. And wouldn't you know it, a train moving at 29 m/s was only 56 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 0.42 s , what minimum acceleration did my car need for me to be here today writing these words?
Physics
1 answer:
vampirchik [111]3 years ago
5 0

Answer:

6.46393559312 m/s²

Explanation:

Time taken to cover 56 m

t=\dfrac{56}{29}\ s

Distance covered in 0.42 seconds

0.42\times 20=8.4\ m

From equation of linear motion

s=ut+\frac{1}{2}at^2

8.4+20(\dfrac{56}{29}-0.42)+\dfrac{1}{2}a(\dfrac{56}{29}-0.42)^2=46\\\Rightarrow a=(46-8.4-20(\dfrac{56}{29}-0.42))\times\dfrac{2}{(\dfrac{56}{29}-0.42)^2}\\\Rightarrow a=6.46393559312\ m/s^2

The minimum acceleration is 6.46393559312 m/s²

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When an 8 V battery is connected to a resistor, a 2 A current flows in the resistor. What is the resistor's value?
Vinvika [58]

Answer:

B

Explanation:

V=IR    I= curren V=volt R=resistor

8=2.R   8/2=R R=4

5 0
3 years ago
A car maintains a constant speed v as it traverses the hill and valley as shown below. Both the hill and valley have a radius of
Zigmanuir [339]

Answer:

As given that the car maintains a constant speed v as it traverses the hill and valley where both the valley and hill have a radius of curvature R.

(i) At point C, the normal force acting on the car is largest because the centripetal force is up. gravity is down and normal force is up. net force is up so magnitude of normal force must be greater than the car's weight.

(ii) At point A, the normal force acting on the car is smallest because the centripetal force is down. gravity is down and normal force is up. net force is up so magnitude of normal force must be less than car's weight.

(iii) At point C, the driver will feel heaviest because the driver's apparent weight is the normal force on her body.

(iv) At point A, the driver will feel the lightest.

(v)The car can go that much fast without losing contact with the road at A can be determined as follow:

Fn=0 - lose contact with road

Fg= mv²/r

mg=mv²/r

v=sqrt (gr)

8 0
3 years ago
A magnet is moved in and out of a coil of wire connected to a high-resistance voltmeter. If the number of coils doubles, the ind
Varvara68 [4.7K]

Answer:

A. Doubles.

Explanation:

In an electromagnetic device such as a generator, when a wire (conductor) moves through the magnetic field between the South and North poles of a magnet, an electromotive force (e.m.f) is usually induced across a wire

The mode of operation of a generator is that a metal core with copper tightly wound to it (conductor coil) rotates rapidly between the two (2) poles of a horseshoe magnet type. Thus when the conductor coil rotates rapidly, it cuts the magnetic field existing between the poles of the horseshoe magnet and then induces the flow of current.

When a high-resistance voltmeter is connected to an electric circuit, a deflection will arise due to the flow of electricity. Moving the magnet towards the coil of wire will cause the needle of the high-resistance voltmeter to move in one direction. Also, as the magnet is moved out from the coil of wire, the needle of the high-resistance voltmeter moves in the opposite direction.

In this scenario, a magnet is moved in and out of a coil of wire connected to a high-resistance voltmeter. If the number of coils doubles, the induced voltage doubles because the number of turns (voltage) in the primary winding is directly proportional to the number of turns (voltage) in the secondary winding.

4 0
3 years ago
Anxious to the point that he couldn't eat very well without his stomach feeling queasy. As a result of his stress, Jonah increas
Mice21 [21]

Based on this information, a psychologist would most likely conclude that Jonah's stress led him toward positive personal changes.

<h3>What is stress?</h3>

When a person is afraid or tensed about something, he overthinks about him and become stressed.

Anxious to the point that he couldn't eat very well without his stomach feeling queasy. As a result of his stress, Jonah increased his time of practicing basketball and asked an old team member to help him develop new skills he needed in order to make the team. After hearing that he made the basketball team a day after tryouts, Jonah went out for a large pizza with the rest of the team players.

As, he is feeling good, he wants to celebrate himself. So, he went to eat pizza with his team players. This shows that he is not stressed but happy.

Thus, ,this information depicts that Jonah's stress led him toward positive personal changes.

Learn more about stress.

brainly.com/question/9643296

#SPJ1

6 0
2 years ago
What is the measuring devices of a mass​
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The measuring devices for mass is scales and Balances
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