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3 years ago

what is the acceleration of a car that slows down from 60m/s to 40 m/s during a period of 10 seconds?

Physics

1 answer:

algol [13]3 years ago

5 0

The acceleration of the car is stated as -2 m/s², while the deceleration of the car is termed as 2 m/s².

Answer:

Explanation:

Acceleration exerted by any object in order of decrease in the speed is termed as deceleration. In other words , negative acceleration or acceleration acting in opposite direction to stop the motion of any object is termed as deceleration. The magnitude of acceleration and deceleration is same only the direction is completely opposite to each other. So the negative sign will be obtained for acceleration value of any object whose velocity slows down from initial velocity.

Here , the initial velocity was 60 m/s and the final velocity is slowed down to 40 m/s in time 10 s.

So acceleration = (Final velocity - Initial velocty)/Time

Acceleration = (40-60)/10 = -20/10 = -2 m/s².

Thus, the acceleration of the car is stated as -2 m/s², while the deceleration of the car is termed as 2 m/s².

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A small rock is thrown straight up with initial speed v0 from the edge of the roof of a building with height H. The rock travels

Crank

Answer:

$v_{avg}=\dfrac{3gH+v_0^2}{v_0+\sqrt{v_0^2+2gH} }$

Explanation:

The average velocity is total displacement divided by time:

$v_{avg} =\dfrac{D_{tot}}{t}$

And in the case of vertical $v_{avg}$

$v_{avg}=\dfrac{y_{tot}}{t}$

where $y_{tot}$ is the total vertical displacement of the rock.

The vertical displacement of the rock when it is thrown straight up from height $H$ with initial velocity $v_0$ is given by:

$y=H+v_0t-\dfrac{1}{2} gt^2$

The time it takes for the rock to reach maximum height is when $y'(t)=0$ , and it is

$t=\frac{v_0}{g}$

The vertical distance it would have traveled in that time is

$y=H+v_0(\dfrac{v_0}{g} )-\dfrac{1}{2} g(\dfrac{v_0}{g} )^2$

$y_{max}=\dfrac{2gH+v_0^2}{2g}$

This is the maximum height the rock reaches, and after it has reached this height the rock the starts moving downwards and eventually reaches the ground. The distance it would have traveled then would be:

$y_{down}=\dfrac{2gH+v_0^2}{2g}+H$

Therefore, the total displacement throughout the rock's journey is

$y_{tot}=y_{max}+y_{down}$

$y_{tot} =\dfrac{2gH+v_0^2}{2g}+\dfrac{2gH+v_0^2}{2g}+H$

$\boxed{y_{tot} =\dfrac{2gH+v_0^2}{g}+H}$

Now wee need to figure out the time of the journey.

We already know that the rock reaches the maximum height at

$t=\dfrac{v_0}{g},$

and it should take the rock the same amount of time to return to the roof, and it takes another $t_0$ to go from the roof of the building to the ground; therefore,

$t_{tot}=2\dfrac{v_0}{g}+t_0$

where $t_0$ is the time it takes the rock to go from the roof of the building to the ground, and it is given by

$H=v_0t_0+\dfrac{1}{2}gt_0^2$

we solve for $t_0$ using the quadratic formula and take the positive value to get:

$t_0=\dfrac{-v_0+\sqrt{v_0^2+2gH} }{g}$

Therefore the total time is

$t_{tot}= 2\dfrac{v_0}{g}+\dfrac{-v_0+\sqrt{v_0^2+2gH} }{g}$

$\boxed{t_{tot}= \dfrac{v_0+\sqrt{v_0^2+2gH} }{g}}$

Now the average velocity is

$v_{avg}=\dfrac{y_{tot}}{t}$

$v_{avg}=\dfrac{\frac{2gH+v_0^2}{g}+H }{\frac{v_0+\sqrt{v_0^2+2gH} }{g} }$

$\boxed{v_{avg}=\dfrac{3gH+v_0^2}{v_0+\sqrt{v_0^2+2gH} } }$

5 0

3 years ago

17. (16 pts) You set up a two-slit experiment with a laser that produces light with a

Natali [406]

when the two waves interfere with eachother to make a dark spot the periodic difference of the two waves is π . the wave length for 2π is 600nm

. ie. for π difference it is 300nm

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3 years ago

What do conduction, radiation, and convection work together to do?

Semmy [17]

Well, conduction is the passing of heat by touch. Convection is the passing along of heat by movement (e.g. hot air rising from a radiator to heat the rest of the room), and radiation is the heating of something through electromagnetic rays without any contact. For example, the earth absorbs the heat radiated from the son (radiation). The air that touches the earth gets warmed up (conduction), and rises, and as it rises, it passes its heat along to more air around it (convection).

6 0

3 years ago

The area of land where water is drained downhill into a body of water is known as a drainage basin, or _______.

GenaCL600 [577]

Water sheds i hope this helps give me a brainiest answer

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A car traveling at 22.4 m/s skids to a stop in 2.55s determine the skidding distance of the car ?

nlexa [21]

8.8 miles. You divide 22.4 & 2.55.

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3 years ago