Which of the following statements is FALSE regarding the law of conservation of energy?

What happens to the force between two charges when each charge is doubled and the distance between them is 1/4 its original

DIA [1.3K]

Answer:

F' = 64 F

Explanation:

The electric force between charges is given by :

$F=\dfrac{kq_1q_2}{r^2}$

Where

q₁ and q₂ are charges

r is the distance between charges

When each charge is doubled and the distance between them is 1/4 its original magnitude such that,

q₁' = 2q₁, q₂' = 2q₂ and r' = (r/4)

New force,

$F'=\dfrac{kq_1'q_2'}{r'^2}$

Apply new values,

$F'=\dfrac{k\times 2q_1\times 2q_2}{(\dfrac{r}{4})^2}\\\\=\dfrac{k\times 4q_1q_2}{\dfrac{r^2}{16}}\\\\=64\times \dfrac{kq_1q_2}{r^2}\\\\=64F$

So, the new force becomes 64 times the initial force.

7 0

2 years ago

1. A perspex box has a 10 cm square base and contains water to a height of 10 cm. A piece of rock of mass 600g is lowered into t

AnnZ [28]

Answer:

(a) The volume of water is 100 cm³

(b) The volume of the rock is 20 cm³

(c) The density of the rock is 30 g/cm³

Explanation:

The given parameters of the perspex box are;

The area of the base of the box, A = 10 cm²

The initial level of water in the box, h₁ = 10 cm

The mass of the rock placed in the box, m = 600 g

The final level of water in the box, h₂ = 12 cm

(a) The volume of water in the box, 'V', is given as follows;

V = A × h₁

∴ The volume of water in the box, V = 10 cm² × 10 cm = 100 cm³

The volume of water in the box, V = 100 cm³

(b) When the rock is placed in the box the total volume, $V_T$ , is given by the sum of the rock, $V_r$ , and the water, V, is given as follows;

$V_T$ = $V_r$ + V

$V_T$ = A × h₂

∴ $V_T$ = 10 cm² × 12 cm = 120 cm³

The total volume, $V_T$ = 120 cm³

The volume of the rock, $V_r$ = $V_T$ - V

∴ $V_r$ = 120 cm³ - 100 cm³ = 20 cm³

The volume of the rock, $V_r$ = 20 cm³

(c) The density of the rock, ρ = (Mass of the rock, m)/(The volume of the rock)

∴ The density of the rock, ρ = 600 g/(20 cm³) = 30 g/cm³

8 0

2 years ago

A car is traveling at 20 km in 15 minutes. What is its average velocity

yarga [219]

The velocity is 4374.45 m/s.
I got the answer by using v=d/t.
20,000meters / 25min= 4,374.45 m/s.

7 0

1 year ago

Explain diffraction at a single slit (light)

Leto [7]

Answer:

At some point on say, the receiving screen, light emanating from the left side of the slit will be out of phase (a difference of 1/2 wavelengths) from light coming from the center of the slit.

Thus for every point that is left of the center of the slit, there will be a point on the right side of the slit that is out of phase,

There will be no light on the screen at that particular point and thus there will be a dark fringe there.

That is the basic explanation for the appearance of dark and bright fringes on the receiving screen.

4 0

1 year ago

Sir Dudley the Dextrous is loading cannons on top of the castle's tallest towers in preparation for an expected attack. He slips

JulsSmile [24]

Answer:

6667.9 J

Explanation:

We are given that

Mass of cannon.m=14 kg

Time,t=3.15 s

Initial velocity,u=0

We have to find the work done by gravity on the falling cannon ball.

$g=9.8 m/s^2$

$h=ut+\frac{1}{2}gt^2$

Substitute the values

$h=0+\frac{1}{2}\times 9.8\times (3.15)^2=48.6 m$

Work done,W=mgh

Using the formula

$W=14\times 9.8\times 48.6=6667.9 J$

4 0

3 years ago