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3 years ago

A rock hits the ground with a speed of 13 m s−1

Physics

1 answer:

polet [3.4K]3 years ago

4 0

Answer:

3.55kg

Explanation:

K. E = ½mv²

Where m = mass, v = velocity

K. E = 300J

v = 13m/s

Therefore,

K. E = ½mv²

300 = ½ × m × 13²

Multiply both sides by 2

600 = m × 169

Divide both sides by 169

m = 600 ÷ 169

mass = 3.55kg

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A ball is released from the top of a tower of height h meters. it takes T seconds to reach the ground . what is the position of

alekssr [168]

Answer:the

8/9 h

Explanation:

Height = 1/2 a T^2 now change to T/3

now height = 1/2 a (T/3)^2 =<u> 1/9</u> 1/2 a T^2 <===== it is 1/9 of the way down or 8/9 h

3 0

2 years ago

Need answer fast plz

vazorg [7]

Answer:

a = 1.20m\ $s^{2}$

Explanation:

225 x 9.8

= 441N

710 - 441

= 269N

$\frac{269}{225}$ = 1.19

a = 1.20

8 0

3 years ago

A photoelectric effect experiment finds a stopping potential of 1.93 V when light of wavelength 200 nm is used to illuminate the

PSYCHO15rus [73]

a) zinc

The equation of the photoelectric effect is:

$E=\phi + K$ (1)

where

E is the energy of the incident light

$\phi$ is the work function

$K$ is the maximum kinetic energy of the emitted photoelectrons

Here the wavelength of the incident light is

$\lambda=200 nm = 2\cdot 10^{-7} m$

so the energy of the light is

$E=\frac{hc}{\lambda}=\frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{2\cdot 10^{-7} m}=9.95\cdot 10^{-19} J$

Converting into electronvolts,

$E=\frac{9.95\cdot 10^{-19}}{1.6\cdot 10^{-19} J/eV}=6.22 eV$ (2)

The stopping potential is the potential needed to stop the photoelectrons with maximum kinetic energy: so, the electrical potential energy corresponding to the stopping potential (V=1.93 V) must be equal to the maximum kinetic energy of the photoelectrons,

$U=q V = K$

and since the charge of the electron is

1 q = 1 e

We have

$K=(1 e)(1.93 V)=1.93 eV$ (3)

Combining (1), (2) and (3), we find the work function of the material:

$\phi = E-K=6.22 eV-1.93 eV=4.29 eV$

So, the cathode is most likely made of zinc, which has a work function of 4.3 eV.

b) The stopping potential does not change

As we said in part A), the stopping potential is proportional to the maximum kinetic energy of the photoelectrons, K.

The intensity of light is proportional to the number of photons that hit the surface of the metal. However, the energy of these photons does not depend on the intensity, but only on the frequency of the light.

Therefore, the energy of the photons (E) does not change when the intensity of light is doubled. Also, the work function $\phi$ does not change: this means that the maximum kinetic energy of the photoelectrons, K, does not change, and so the stopping potential remains the same.

6 0

3 years ago

A spring-loaded gun has a spring for which

e-lub [12.9K]

Answer:

7.5 m

Explanation:

k = Spring constant = 180 N/m

x = Displacement of spring = 14 cm

m = Mass of projectile = 0.024 kg

a = g = Acceleration due to gravity = $9.81\ \text{m/s}^2$

s = Displacement of projectile

v = Final velocity = 0

u = Initial velocity

The potential energy of the spring will be equal to the kinetic energy of the object

$\dfrac{1}{2}kx^2=\dfrac{1}{2}mu^2\\\Rightarrow u=\sqrt{\dfrac{kx^2}{m}}\\\Rightarrow u=\sqrt{\dfrac{180\times 0.14^2}{0.024}}\\\Rightarrow u=12.12\ \text{m/s}$

$v^2-u^2=2as\\\Rightarrow s=\dfrac{v^2-u^2}{2a}\\\Rightarrow s=\dfrac{0-12.12^2}{2\times -9.81}\\\Rightarrow s=7.5\ \text{m}$

The maximum height reached above the initial position is 7.5 m

5 0

3 years ago

What is the unit for coefficient of kinetic friction?

-BARSIC- [3]

It has no units. <span>
The coefficient of friction is dimensionless:
[force]/[force] = Newton/Newton = 1</span>

3 0

4 years ago