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4 years ago

a level physics moments question please explain how the answer to (a) is 7.5N and the answer to (b) is 5.7N

Physics

1 answer:

Mkey [24]4 years ago

5 0

Explanation:

a) Sum of moments about the pivot:

∑τ = Iα

(10 kg × 10 m/s²) (0.3 m) + F (-0.4 m) = 0

F = 75 N

b) Sum of moments about the pivot:

∑τ = Iα

(20 N) (0.3 m) + (20 N) (-0.2 m) + F (-0.7 m) = 0

6 Nm − 4 Nm + F (-0.7 m) = 0

F = 2.9 N

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Two charges, X and Y, are placed along the x-axis. Charge X is +18 nC and is placed at x = 0. Charge Y is placed at a location o

Helen [10]

Answer:

Charge Z can be placed at x = -2.7 m or at x = 0.27 m.

Explanation:

The Coulomb force between two charges, $Q_1$ and $Q_2$ , separated by a distance, $d$ , is given

$F = k\dfrac{Q_1Q_2}{r^2}$

k is a constant.

For the charge Z to be at equilibrium, the force exerted on it by charge X must be equal and opposite to the force exerted on it by charge Y.

It is to be placed along the x-axis. Hence, it is on the same line as charges X and Y.

Let the charge on Z be Q. It is positive.

Let the distance from charge X be x m. Then the distance from charge Y will be (0.60 - x) m.

Force due to charge X

$F_X = k\dfrac{18Q}{x^2}$

Force due to charge Y

$F_Y = k\dfrac{-27Q}{(0.60-x)^2}$

Since both forces are equal and opposite,

$F_X = -F_Y$

$k\dfrac{18Q}{x^2} = -k\dfrac{-27Q}{(0.60-x)^2}$

$\dfrac{2}{x^2} = \dfrac{3}{(0.60-x)^2}$

$2(0.60-x)^2 = 3x^2$

$2(0.36-1.20x+x^2) = 3x^2$

$0.72-2.40x+2x^2 = 3x^2$

$x^2+2.40x-0.72 = 0$

Applying the quadratic formula,

$x = \dfrac{-2.40\pm\sqrt{2.40^2 - (4)(1)(-0.72)}}{2} = \dfrac{-2.40\pm\sqrt{8.64}}{2}$

$x = -2.7$ or $x = 0.27$

Charge Z can be placed at x = -2.7 m or at x = 0.27 m

3 0

4 years ago

Liz puts a 1 kg weight and a 10 kg on identical sleds. She then applies a 10N force to each sled. Which does not explain why the

Mariana [72]

Answer: C

Explanation:
The acceleration does not depend directly on the mass of the object.

Newton's Law is Force = Mass x Acceleration.
Therefore, Acceleration = Force/Mass

The same force is applied in both cases.
Therefore acceleration is inversely proportional to mass.
As mass decreases, acceleration increases.

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4 years ago

Read 2 more answers

If rho(x,y) is the density of a wire (mass per unit length), then

lidiya [134]

Answer:

See description

Explanation:

With the given information we have:

$x(t) = 1 + cos(t)\\ y(t)=sin(t)\\ \rho(x,y) = 3x$

the interval is $[0,\pi ]$

now the mass $m$ has the given expression:

$m = \int \rho(x,y) dS$

we will use the formula for a line integral and let:

$dS=\sqrt{x'(t)^2 + y'(t)^2}=\sqrt{cos(t)^2 + sin(t)^2}dt=dt$

therefore we have:

$m=\int \rho(x,y)dS=\int\limits^\pi_0 {3*x}dS=\int\limits^\pi _0{3*(1+cos(t))dS\\=\int\limits^\pi _0{3*(1+cos(t))dt$

we solve the integral:

$m=3*\int\limits^\pi _0{(1+cos(t))dt= 3*(t+sin(t))\limits^\pi _0=3*\pi=9.42$

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3 years ago

Question 10 of 10Which statements are true?Check all that apply.O A. If heat is added to a substance, the temperature alwaysincr

inna [77]

The true statements are B and C.

This comes from the following facts:

Even when heat is added to a substance in a change of phase the temperature does not increases since this heat is latent heat.

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1 year ago

How were the fossil symbols and mountain belts helpful in deciding where to move the continents

devlian [24]

Hey there!

The fossil symbols and mountain belts provided clues as to where and how the continents were connected together before they had moved. The mountain belts showed scientists the direction those plates moved and the fossils indicated that similar dinosaurs or animals lived together in the same area.

Thank you!

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3 years ago

a level physics moments question please explain how the answer to (a) is 7.5N and the answer to (b) is 5.7N​

a level physics moments question please explain how the answer to (a) is 7.5N and the answer to (b) is 5.7N