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3 years ago

5

A small box slides down a ramp on a friction with surface. If the total energy of the system is conserved, which computational m

odel expresses the kinetic energy of the box?

2 answers:

spayn [35]3 years ago

6 0

Answer:

WWWEEEEEEEEEEEEEEEEEE

Explanation:

OlgaM077 [116]3 years ago

6 0

B. KEsubbox = Esubtotal - mgh

If you are modeling a system in which an object’s total energy is conserved, you could express potential energy as the difference between total and kinetic, or, alternatively, you could model kinetic energy as the difference between total and potential.

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8. Rubbing a plastic bag and a balloon with a cloth gives both objects a net negative charge. The balloon's

Dafna1 [17]

Answer:

0.214 m

Explanation:

In order for the bag to levitate and not fall down, the electrostatic force between the bag and the balloon must balance the weight of the bag.

Therefore, we can write:

$k\frac{q_1 q_2}{r^2}=mg$

where

k is the Coulomb constant

$q_1=-1\cdot 10^{-10}C$ is the charge on the balloon

$q_2=-1\cdot 10^{-5} C$ is the charge on the bag

r is the separation betwen the bag and the balloon

$m=0.02 g=2\cdot 10^{-5} kg$ is the mass of the bag

$g=9.8 m/s^2$ is the acceleration due to gravity

Solving for r, we find the distance at which the bag must be held:

$r=\sqrt{\frac{kq_1 q_2}{mg}}=\sqrt{\frac{(9\cdot 10^9)(-1\cdot 10^{-10})(-1\cdot 10^{-5})}{(2\cdot 10^{-5})(9.8)}}=0.214 m$

5 0

3 years ago

What are 5 differences of Scientific Theories vs Scientific Laws and how they are simular

aleksandr82 [10.1K]

Explanation:

1 .Theories are not as accurate as laws

2 Both of them are based on scientific events

3. theories are opnions

4 .laws are fixed

5. not all theories are scientific

3 0

3 years ago

If one has twice the length of the other, what is the ratio of the diameter of the longer wire to the diameter of the shorter wi

hram777 [196]

Explanation:

The resistance of a wire is given by the formula as follows :

$R=\rho \dfrac{l}{A}$

l is length of wire

A is area of cross section, $A=\pi r^2$

Since, r=d/2, d = diameter

$A=\pi \dfrac{d^2}{4}$

It is given in the problem that the resistance of two aluminum wires is same.

$R_1=R_2\\\\\rho\dfrac{L_1}{\pi d_1^2/4}=\rho\dfrac{L_2}{\pi d_2^2/4}\\\\\dfrac{L_1}{L_2}=\dfrac{d_1^2}{d_2^2}$

We have, L₁=2L₂

So,

$\dfrac{2L_2}{L_2}=\dfrac{d_1^2}{d_2^2}\\\\\dfrac{d_1^2}{d_2^2}=2\\\\\dfrac{d_1}{d_2}=\sqrt{2}$

So, the ratio of the diameter of the longer wire to the diameter of the shorter wire is $\sqrt2:1$

6 0

4 years ago

A rock is thrown 0.8 meters into the air. Find how fast it was thrown.

natita [175]

Answer:3.96 m/s

Explanation:

Given

Rock is thrown to a height of 0.8 m

We know that energy is conserved

Total Energy=kinetic Energy+Potential Energy

At bottom Kinetic Energy is maximum and Potential energy is minimum while at the top potential Energy is maximum and kinetic energy is minimum

Energy at Bottom $E_b=\frac{1}{2}mv^2+0$

Energy at Top $E_t=0+mgh$

Thus

$E_t=E_b$

$mgh=\frac{1}{2}mv^2$

$v=\sqrt{2gh}$

$v=\sqrt{2\times 9.8\times 0.8}$

$v=\sqrt{15.68}$

$v=3.96\ m/s$

5 0

4 years ago

A remote controlled airplane moves 7.2 m in 2.5seconds what is the plane’s velocity

Vsevolod [243]

Answer:

2.88m/s

Explanation:

Given parameters:

Displacement = 7.2m

Time taken = 2.5s

Unknown:

Velocity of the plane = ?

Solution:

Velocity is the displacement divided by the time taken.

Velocity = $\frac{displacement}{time taken}$

So;

Velocity = $\frac{7.2}{2.5}$ = 2.88m/s

4 0

3 years ago