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dem82 [27]
2 years ago
6

Polly is pushing a box across the floor with a force of 30 n. the force of gravity is –8 n, and the normal force is 8 n. which v

alue could describe the force of friction if polly could not move the box?–30 n–8 n8 n30 n
Physics
2 answers:
aliina [53]2 years ago
6 0

Answer:

Force of friction, F = -30 N

Explanation:

It is given that, Polly is pushing a box across the floor with a force of 30 N. The force of gravity is –8 N, and the normal force is 8 N.

We know that the frictional force is an opposing force. It always opposes the motion. It acts in the direction opposite to the direction of motion.

In this case, the box is pulled with a force of 30 N. So, the force of friction so that the box does not move will be 30 N but it acts in opposite direction.

So, the correct option is (a) " -30 N".

Rudiy272 years ago
3 0
It's -30N is the correct answer
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Answer: a. m = 7.7 kg

              b. V = 435.52 in³

              c. m = 1927 kg

              d. V = 335.37 cm³

              e. m = 3 kg

Explanation: <u>Density</u> is the ratio of mass per volume, i.e., it's the measure of an object's compactness. Its representation is the greek letter ρ.

The formula for density is

\rho=\frac{m}{V}

Density's unit in SI is kg/m³, but it can assume lots of other units.

Some unit transformations necessary for the resolution of the question:

1 L = 1 dm³ = 1000 cm³

1 in³ = 16.3871 cm³

1 g = 0.001 kg

a. V = 1.34 L = 1340 cm³

\rho=\frac{m}{V}

m=\rho.V

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m = 7705 g => 7.705 kg

Mass of object 1 with volume 1.34L is 7.7 kg.

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V = 7.58³

V = 435.52 in³

Volume of object 2 is 435.52 in³.

c. Using 1 in³ = 16.3871 cm³ to change units:

V = 435.52 * 16.3871

V = 713689.4 cm³

Then, mass will be

m=\rho.V

m = 2.7 * 713689.4

m = 1926961.4 g => 1927 kg

Mass of object 2 is 1927 kg.

d. Volume of a sphere is calculated as V=\frac{4}{3}.\pi.r^{3}

Diameter is twice the radius, then r = 4.31 cm.

Volume is

V=\frac{4}{3}.\pi.(4.31)^{3}

V = 335.37 cm³

Volume of object 3 is 335.37 cm³.

e. m=\rho.V

m = 8.96 * 335.37

m = 3004.91 g => 3 kg

Mass of object 3 is 3 kg.

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Answer:

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for this exercise in geometric optics let's use the equation of the constructor

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