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Ksju [112]
3 years ago
5

Three equal point charges, each with charge 1.25 μC , are placed at the vertices of an equilateral triangle whose sides are of l

ength 0.450 m . What is the electric potential energy U of the system
Physics
1 answer:
natali 33 [55]3 years ago
7 0

Answer:

electric potential energy  is 9.36 ×10^{-2} J

Explanation:

given data

charge q = 1.25 μC =1.25×10^{-6} C

length L = 0.450 m

to find out

electric potential energy

solution

we apply electric potential energy U formula

U = U1 + U2 + U3   .................1

we know magnitude of all three charge is

q = q1 = q2 = q3

so here from 1

U = 1 / 4π∈ × (q²/L + q²/L +q²/L )

U = 1 / 4π∈ × 3(q²/L)

put here all value and we know ∈ = 8.85 ×10^{-12} F/m

U = 1 / 4π( 8.85 ×10^{-12}) × ( 3 (1.25×10^{-6})² / 0.450 )

U = 8.99×10^{9} × ( 3 (1.25×10^{-6})² / 0.450 )

U = 9.36 ×10^{-2}

so electric potential energy  is 9.36 ×10^{-2} J

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A car driver traveling at a speed of 108km per hour ,sees a traffic light and stopped after travelling for 20seconds .Find the a
navik [9.2K]

Answer:

– 2.5 m/s²

Explanation:

We have,

• Initial velocity, u = 180 km/h = 50 m/s

• Final velocity, v = 0 m/s (it stops)

• Time taken, t = 20 seconds

We have to find acceleration, a.

\longrightarrow a = (v ― u)/t

\longrightarrow a = (0 – 50)/20 m/s²

\longrightarrow a = –50/20 m/s²

\longrightarrow a = – 5/2 m/s²

\longrightarrow a = – 2.5 m/s² (Velocity is decreasing) [Answer]

6 0
3 years ago
The maximum wavelength For photoelectric emissions in tungsten is 230 nm. What wavelength of light must be use in order for elec
notka56 [123]

Answer:

λ = 1.8 x 10⁻⁷ m = 180 nm

Explanation:

First we find the work function of tungsten by using the following formula:

∅ = hc/λmax

where,

∅ = work function = ?

h = Plank's Constant = 6.626 x 10⁻³⁴ J.s

c = speed of light = 3 x 10⁸ m/s

λmax = maximum wavelength for photoelectric emission = 230 nm

λmax = 2.3 x 10⁻⁷ m

Therefore,

∅ = (6.626 x 10⁻³⁴ J.s)(3 x 10⁸ m/s)/(2.3 x 10⁻⁷ m)

∅ = 8.64 x 10⁻¹⁹ J

Now we convert Kinetic Energy of electron into Joules:

K.E = (1.5 eV)(1.6 x 10⁻¹⁹ J/1 eV)

K.E = 2.4 x 10⁻¹⁹ J

Now, we use Einstein's Photoelectric Equation:

Energy of Photon = ∅ + K.E

Therefore,

Energy of Photon = 8.64 x 10⁻¹⁹ J + 2.4 x 10⁻¹⁹ J

Energy of Photon = 11.04 x 10⁻¹⁹ J

but,

Energy of Photon = hc/λ

where,

λ = wavelength of light = ?

Therefore,

11.04 x 10⁻¹⁹ J = (6.626 x 10⁻³⁴ J.s)(3 x 10⁸ m/s)/λ

λ = (6.626 x 10⁻³⁴ J.s)(3 x 10⁸ m/s)/(11.04 x 10⁻¹⁹ J)

<u>λ = 1.8 x 10⁻⁷ m = 180 nm</u>

5 0
3 years ago
While standing at the edge of the roof of a building, you throw a stone upward with an initial speed of 5.65 m/s. The stone subs
xxTIMURxx [149]

Answer:

1. 20.54m/s

2. 1.52s

Explanation:

QUESTION 1:

The speed the stone impact the ground is the final speed/velocity, which can be calculated using the formula:

v² = u² + 2as

Where;

v = final velocity (m/s)

u = initial velocity (m/s)

a = acceleration due to gravity (m/s²)

s = distance (m)

From the provided information, u = 5.65m/s, v = ?, s = 19.9m, a = 9.8m/s²

v² = 5.65² + 2 (9.8 × 19.9)

v² = 31.9225 + 2 (195.02)

v² = 31.9225 + 390.04

v² = 421.9625

v = √421.9625

v = 20.5417

v = 20.54m/s

QUESTION 2:

Using v = u + at

Where v = final velocity (m/s) = 20.54m/s

t = time (s)

u = initial velocity (m/s) = 5.65m/s

a = acceleration due to gravity (m/s²)

v = u + at

20.54 = 5.65 + 9.8t

20.54 - 5.65 = 9.8t

14.89 = 9.8t

t = 14.89/9.8

t = 1.519

t = 1.52s

3 0
3 years ago
A 1000 kg truck moving at 2.0 m/s runs into a concrete wall. It takes 0.5 s for the truck to completely stop. What is the magnit
guajiro [1.7K]

Answer:

Momentum is given by

p

=

m

v

. Impulse is the change of momentum,

I

=

Δ

p

and is also equal to force times time:

I

=

F

t

. Rearranging,

F

=

I

t

=

Δ

p

t

=

0

−

20

,

000

5

=

−

4000

N

.

Explanation:

Momentum before the collision is

p

=

m

v

=

2000

⋅

10

=

20

,

000

k

g

m

s

−

1

.

Assuming the truck comes to a complete halt, the momentum after the collision is

0

k

g

m

s

−

1

.

The change in momentum,

Δ

p

, is initial minus final

→

0

−

20

,

000

=

−

20

,

000

This is called the impulse:

I

=

Δ

p

. Impulse is also equal (check the units) to force times time:

I

=

F

t

.

We can rearrange this expression to make

F

the subject:

F

=

I

t

=

Δ

p

t

=

−

20

,

000

5

=

−

4000

N

The negative sign just means the force acting is in the opposite direction to the initial momentum.

(This will be the average force acting during the collision: collisions are chaotic so the force is unlikely to be constant.)

3 0
3 years ago
An 100W light bulb is on 6 hours work out the energy (kWh) used and the cost of it (1kWh = £0.1359) with working out please
Ainat [17]
1,000 W  =  1 kW
100 W  =  0.1 kW

           (0.1 kW) x (6 h) = 0.6 kWh    <=== energy

           (0.6 kWh) x (£0.1359/kWh)  =  £0.0815     <=== cost of it     
8 0
3 years ago
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