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3 years ago

Please help it’s the end the semester test

Physics

1 answer:

liq [111]3 years ago

6 0

Battery and electricity are matter ..

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A seesaw is 4.0m long with a pivot at its midpoint. A boy who weighs 400N sits at a distance of 1.5m from the pivot. His sister

bezimeni [28]

Answer:

the girl must sit 2 cm from the pivot at the opposite end of the seesaw.

Explanation:

Given;

length of the seesaw, L = 4.0 m

weight of the boy, W₁ = 400 N

position of the boy from the pivot, d₁ = 1.5 m

weight of her sister, W₂ = 300 N

First, make a sketch of this information given;

0---0.5m---------------------Δ--------------------------4m

↓<--------1.5m-------> <---------x--------->↓

400 N 300N

Apply the principle of moment about the pivot, to determine the value of x;

Sum of anticlockwise moment = sum of clockwise moment

400(1.5) = 300(x)

600 = 300x

x = 600/300

x = 2 cm

Thus, the girl must sit 2 cm from the pivot at the opposite end of the seesaw.

8 0

3 years ago

A wire with a length of 150 m and a radius of 0.15 mm carries a current with a uniform current density of 2.8 x 10^7A/m^2. The c

Mrac [35]

Answer:

The current is 2.0 A.

(A) is correct option.

Explanation:

Given that,

Length = 150 m

Radius = 0.15 mm

Current density $J=2.8\times10^{7}\ A/m^2$

We need to calculate the current

Using formula of current density

$J = \dfrac{I}{A}$

$I=J\timesA$

Where, J = current density

A = area

I = current

Put the value into the formula

$I=2.8\times10^{7}\times\pi\times(0.15\times10^{-3})^2$

$I=1.97=2.0\ A$

Hence, The current is 2.0 A.

7 0

3 years ago

A ray in glass arrives at the glass-water interface at an angle of 48° with the normal. The refracted ray, in water, makes a 72°

dimaraw [331]

Answer:

50.4°

Explanation:

Snell's law states:

n₁ sin θ₁ = n₂ sin θ₂

where n is the index of refraction and θ is the angle of incidence (relative to the normal).

When θ₁ = 48°:

n sin 48° = 1.33 sin 72°

n = 1.702

When θ₁ = 37°:

1.702 sin 37° = 1.33 sin θ

θ = 50.4°

3 0

3 years ago

What is the ability to react with air

Bond [772]

Reactivity is the answer

3 0

3 years ago

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Why does magnet 5 float above magnet 4

4vir4ik [10]

Because the same sides(N and N, or S and S) are facing each other in magnet 4 and 5. Also in magnet 2 and 3.

8 0

3 years ago