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2 years ago

What would the acceleration of a car be from a stoplight if it started at 0 m/s and reached a

Physics

1 answer:

trapecia [35]2 years ago

3 0

Answer:

The acceleration of a car would be: $a=12.8$ m/s²

Explanation:

Given

Initial velocity = $v_1=0$ m/s

Final velocity = $v_f=100$ m/s

Time elapsed = $t = 7.8$ s

To determine

We need to determine the acceleration of a car.

We know that acceleration is basically the rate of change in velocity over time.

Thus,

We can determine the acceleration using the formula

$\:\:\:a=\:\frac{v_f-v_i}{t}$

where

$a$ is the acceleration

$v_1$ is the initial velocity

$v_f$ is the final velocity

$t$ is time elapsed

now substituting the values $v_1=0$ , $v_f=100$ , and $t = 7.8$ in the formula

$\:\:\:a=\:\frac{v_f-v_i}{t}$

$a=\:\frac{100-0}{7.8}$

$a=\frac{100}{7.8}$

$a=12.8$ m/s²

Therefore, the acceleration of a car would be: $a=12.8$ m/s²

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3 years ago

Read 2 more answers

A 124-kg balloon carrying a 22-kg basket is descending with a constant downward velocity of 20.0 m/ s. A I.O-kg stone is thrown

nadya68 [22]

(a) 296.6 m

The motion of the stone is the motion of a projectile, thrown with a horizontal speed of

$v_x = 15.0 m/s$

and with an initial vertical velocity of

$v_{y0} = -20.0 m/s$

where we have put a negative sign to indicate that the direction is downward.

The vertical position of the stone at time t is given by

$y(t) = h + v_{0y} t + \frac{1}{2}gt^2$ (1)

where

h is the initial height

g = -9.81 m/s^2 is the acceleration due to gravity

The stone hits the ground after a time t = 6.00 s, so at this time the vertical position is zero:

y(6.00 s) = 0

Substituting into eq.(1), we can solve to find the initial height of the stone, h:

$0 = h + v_{0y} y + \frac{1}{2}gt^2\\h = -v_{0y} y - \frac{1}{2}gt^2=-(-20.0 m/s)(6.00 s) - \frac{1}{2}(9.81 m/s^2)(6.00 s)^2=296.6 m$

(b) 176.6 m

The balloon is moving downward with a constant vertical speed of

$v_y = -20 m/s$

So the vertical position of the balloon after a time t is

$y(t) = h + v_y t$

and substituting t = 6.0 s and h = 296.6 m, we find the height of the balloon when the rock hits the ground:

$y(t) = 296.6 m + (-20.0 m)(6.00 s)=176.6 m$

(c) 198.2 m

In order to find how far is the rock from the balloon when it hits the ground, we need to find the horizontal distance covered by the rock during the time of the fall.

The horizontal speed of the rock is

$v_x = 15.0 m/s$

So the horizontal distance travelled in t = 6.00 s is

$d_x = v_x t = (15.0 m/s)(6.00 s)=90 m$

Considering also that the vertical height of the balloon after t=6.00 s is

$d_y = 176.6 m$

The distance between the balloon and the rock can be found by using Pythagorean theorem:

$d=\sqrt{(90 m)^2+(176.6 m)^2}=198.2 m$

(di) 15.0 m/s, -58.8 m/s

For an observer at rest in the basket, the rock is moving horizontally with a velocity of

$v_x = 15.0 m/s$

Instead, the vertical velocity of the rock for an observer at rest in the basket is

$v_y (t) = gt$

Substituting time t=6.00 s, we find

$v_y = (-9.8 m/s)(6.00 s)=-58.8 m/s$

(dii) 15.0 m/s, -78.8 m/s

For an observer at rest on the ground, the rock is still moving horizontally with a velocity of

$v_x = 15.0 m/s$

Instead, the vertical velocity of the rock for an observer on the ground is now given by

$v_y (t) = v_{0y} + gt$

Substituting time t=6.00 s, we find

$v_y = (-20.0 m/s)+(-9.8 m/s)(6.00 s)=-78.8 m/s$

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2 years ago

PLEASE HELP ME!!!!! You draw an arrow from left to right on a piece of paper and place the paper well behind a glass of water. Y

julia-pushkina [17]

Answer:

I think it is the first one: The arrow appears reversed because light is bent as it enters the water, and again as it exits. The two light paths cross, making the direction of the arrow appear crossed.

Explanation:

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2 years ago

Sallys physical education teacher timed her run and recorded the time and distance in the table below. What is her average speed

Fudgin [204]

Answer: B) 2.5 m/s

Explanation: Find the average of the time and distance, and see how far they go in only 1 second.

1 + 2 + 3 + 4 + 5 = 15
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2 + 5 + 7 + 10 + 12 = 36
36 divided by 5 = 7.2

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7.2 divided by 3 = 2.4

Therefore, the answer is technically 2.4m/s

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3 years ago

Is V directly proportional to I (From V=IR)?? Or is V inversely proportional to I (From P=IV) ???

ziro4ka [17]

First of all, I is proportional V according to the Ohm's Law. R is merely a constant you need to obtain an equation. However, it is true that R changes with temperature and pressure, therefore Ohm's Law is only applicable in an invariable environment. Also this constant R is different for different materials.

So, do not get confused.

Ohm's law is not a universal law, please remember that as well. Some materials do not follow it and we call them non-ohmic conductors. I hope I helped! ^-^

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3 years ago