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3 years ago

What kind of stored energy enables a stretched bow to shoot an arrow?

Physics

2 answers:

blsea [12.9K]3 years ago

7 0

Sorry if im wrong but I'll say kinetic energy

Hope it helps:)

Aliun [14]3 years ago

6 0

Stretching increases potential of the bow since its elastic.

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An electron has a kinetic energy of 3.00 ev. find its wavelength. (b) what if? a photon has energy 3.00 ev. find its wavelength.

Harman [31]

(a) The electron kinetic energy is
$K=3.00 eV$
which can be converted into Joule by keeping in mind that
$1 eV=1.6 \cdot 10^{-19}eV$
So that we find
$K=3.00 eV \cdot 1.6 \cdot 10^{-19} eV/J =4.8 \cdot 10^{-19}J$

The kinetic energy of the electron is related to its momentum p by:
$K= \frac{p^2}{2m}$
where m is the electron mass. Re-arranging the equation, we find
$p= \sqrt{ 2Km}= \sqrt{ 2 ( 4.8 \cdot 10^{-19} J)(9.1 \cdot 10^{-31} kg) } =9.35 \cdot 10^{-25} kgm/s$

And now we can use De Broglie's relationship to find its wavelength:
$\lambda= \frac{h}{p}= \frac{6.6 \cdot 10^{-34} Js}{9.35 \cdot 10^{-25} kg m/s} =7.06 \cdot 10^{-10}m$
where h is the Planck constant.

(b) By using the same procedure of part (a), we can convert the photon energy into Joules:
$E=3.00 eV \cdot 1.6 \cdot 10^{-19} eV/J =4.8 \cdot 10^{-19}J$

The energy of a photon is related to its frequency f by:
$E=hf$
where h is the Planck constant. Re-arranging the equation, we find
$f= \frac{E}{h}= \frac{4.8 \cdot 10^{-19} J}{6.6 \cdot 10^{-34}Js} =7.27 \cdot 10^{14}Hz$

And now we can use the relationship between frequency f, speed of light c and wavelength $\lambda$ of a photon, to find its wavelength:
$\lambda= \frac{c}{f}= \frac{3 \cdot 10^8 m/s}{7.27 \cdot 10^{14} Hz} =4.13 \cdot 10^{-7} m$

8 0

3 years ago

At what distance from a long, straight wire carrying a current of 8.7 A is the magnetic field due to the wire equal to the stren

deff fn [24]

Answer:

r= 3.2 cm

Explanation:

Given that

I= 8.7 A

B= 5.4 x 10⁻⁵ T

μo=1.25664 x 10⁻⁶

We know that magnetic filed in wire at a distance r given as

$B=\dfrac{\mu_oI}{2\pi r}$

$r=\dfrac{\mu_oI}{2\pi B}$

By putting the values

$r=\dfrac{1.25664\times 10^{-6}\times 8.7}{2\times \pi \times 5.4\times 10^{-5}}\ m$

r=0.032 m

r= 3.2 cm

5 0

3 years ago

A woman exerts a horizontal force of 113 N on a crate with a mass of 31.2 kg.

sergeinik [125]

Answer:

a) 113N

b) 0.37

Explanation:

a) Using the Newton's second law:

\sum Fx =ma

Since the crate doesn't move (static), acceleration will be zero. The equation will become:

\sum Fx = 0

\sumFx = Fm - Ff = 0.

Fm is the applied force

Ff is the frictional force

Since Fm - Ff = 0

Fm = Ff

This means that the applied force is equal to the force of friction if the crate is static.

Since applied force is 113N, hence the magnitude of the static friction force will also be 113N

b) Using the formula

Ff = nR

n is the coefficient of friction

R is the reaction = mg

R = 31.2 × 9.8

R = 305.76N

From the formula

n = Ff/R

n = 113/305.76

n = 0.37

Hence the minimum possible value of the coefficient of static friction between the crate and the floor is 0.37

8 0

2 years ago

How much kinetic energy does a moving 6 kg object have If It moves with a velocity of<br> 3 m/s?

Brut [27]

K.E =1/2mv2
M=6kg
V=3m/s
K.E=1/2 X 6 X 3 X 3
=1/2 X 6 X 9
=27 J

8 0

2 years ago

Uses of convace, convex mirror

Leya [2.2K]

Answer:

The concave mirror is a converging mirror so that it is used for many purposes, It is used as a torch to reflect the light, It is used in the aircraft landing at the airports to guide the aeroplanes, It is used in shaving to get an enlarged and erect image of the face.

Explanation:

3 0

2 years ago