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2 years ago

An object starts from rest and uniformly accelerates at a rate of 1.25 m/s2 for 7.0 seconds.

Physics

1 answer:

stich3 [128]2 years ago

8 0

Explanation:

Since its accelerating, the velocity vs time graph is linear

For displacement we need initial velocity (which is zero because it starts from rest) and final velocity (which is calculatee thro acceleration formula

A= (vf - vi)/t

a= vf-0/t

1.25=vf / 7

1.25*7=vf

8.75 = vf

Now for displacement plug all the values in

X = 1/2(vf-vi)/t formula

The displacement (x) is 30.625 m

For part 3, we know new displacement that is 22m , the final and initial velocities are the same so just plug in the values for same formula above

The answer is t = 5.02

Im pretty sure all the answers are correct

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Find the potential energy of a 2kg ball 15m in the air

Paraphin [41]

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3 years ago

Which of the following has the greatest momentum? *

denis-greek [22]

Answer:

Tortoise with a mass of 270 kg moving at a velocity of 0.5 m/s

Explanation:

From the question above,

(1) tortoise with a mass of 270 kg moving at a velocity of 0.5 m/s

Mometum = mass×velocity

Momentum = 270×0.5

Momentum = 135 kgm/s

(2) hare with a mass of 2.7 kg moving at a velocity of 7 m/s

Mementum = mass × velocity

Momentum = 2.7×7

Momentum = 18.9 kgm/s

(3) turtle with a mass of 91 kg moving at a velocity of 1.4 m/s

Momentum = mass × velocity

Momentum = 91×1.4

Momentum = 127.4 kgm/s

(4) roadrunner with a mass of 1.8 kg moving at a velocity of 6.7 m/s

Momentum = mass × velocity

Momentum = 1.8×6.7

Momentum = 12.06 kgm/s

From the above, the one with the greatest momentum is tortoise with a mass of 270 kg moving at a velocity of 0.5 m/s

3 0

2 years ago

What is the energy of a photon that has the same wavelength as an electron having a kinetic energy of 15 ev?

serg [7]

Answer: $6.268(10)^{-16}J$

Explanation:

The kinetic energy of an electron $K_{e}$ is given by the following equation:

$K_{e}=\frac{(p_{e})^{2} }{2m_{e}}$ (1)

Where:

$K_{e}=15eV=2.403^{-18}J=2.403^{-18}\frac{kgm^{2}}{s^{2}}$

$p_{e}$ is the momentum of the electron

$m_{e}=9.11(10)^{-31}kg$ is the mass of the electron

From (1) we can find $p_{e}$ :

$p_{e}=\sqrt{2K_{e}m_{e}}$ (2)

$p_{e}=\sqrt{2(2.403^{-18}J)(9.11(10)^{-31}kg)}$

$p_{e}=2.091(10)^{-24}\frac{kgm}{s}$ (3)

Now, in order to find the wavelength of the electron $\lambda_{e}$ with this given kinetic energy (hence momentum), we will use the De Broglie wavelength equation:

$\lambda_{e}=\frac{h}{p_{e}}$ (4)

Where:

$h=6.626(10)^{-34}J.s=6.626(10)^{-34}\frac{m^{2}kg}{s}$ is the Planck constant

So, we will use the value of $p_{e}$ found in (3) for equation (4):

$\lambda_{e}=\frac{6.626(10)^{-34}J.s}{2.091(10)^{-24}\frac{kgm}{s}}$

$\lambda_{e}=3.168(10)^{-10}m$ (5)

We are told the wavelength of the photon $\lambda_{p}$ is the same as the wavelength of the electron:

$\lambda_{e}=\lambda_{p}=3.168(10)^{-10}m$ (6)

Therefore we will use this wavelength to find the energy of the photon $E_{p}$ using the following equation:

$E_{p}=\frac{hc}{lambda_{p}}$ (7)

Where $c=3(10)^{8}m/s$ is the spped of light in vacuum

$E_{p}=\frac{(6.626(10)^{-34}J.s)(3(10)^{8}m/s)}{3.168(10)^{-10}m}$

Finally:

$E_{p}=6.268(10)^{-16}J$

4 0

3 years ago

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dangina [55]

The answer would be it will be longer than the 656.3 nm. The reduced mass of positronium is less than hydrogen so the photon energy will be a reduced amount of for positronium than for hydrogen. So this will mean that the wavelength will be lengthier.

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3 years ago

Rays of light coming from the sun (a very distant object) are near and parallel to the principal axis of a concave mirror. After

Setler [38]

A concave mirror is an example of curved mirrors. So that the appropriate answer to the given question is option D. The rays will cross at the focal point.

A concave mirror is a type of mirror in which its inner part is the reflecting surface, while its outer part is the back of the mirror. This mirror reflects all parallel rays close to the principal axis to a point of convergence. It can also be referred to as the converging mirror.

In this type of mirror, all rays of light parallel to the principal axis of the mirror after reflection will cross at the focal point.

Therefore, the required answer to the given question is option D. i.e The rays will cross at the focal point.

For reference: brainly.com/question/20380620

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2 years ago