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3 years ago

10

Which of the following examples illustrates static friction in action?

2 answers:

Slav-nsk [51]3 years ago

7 0

<h3><u>Answer;</u></h3>

<em>D. a car starting to move after the light changes from red to green</em>

<h3><u>Explanation;</u></h3>

<u><em>Static friction</em></u> is a type of friction or a force that is experienced by a body or a substance at rest. Therefore, when a force is applied on a body or an object at rest it opposes the static friction.
<em><u>Static friction </u></em>does not have the ability to move an object or induce motion since it is countered by other strong opposite forces. Static friction must be overcome to cause motion of the object.
When a <em><u>body or an object is in motion it experiences kinetic friction</u></em>. Therefore, when a body at rest starts to move then the friction changes to kinetic friction.

lilavasa [31]3 years ago

3 0

I think its d. but im not sure

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Please just give me an answer, thanks.

Colt1911 [192]

#1

$\\ \rm\dashrightarrow P=VI\implies V=\dfrac{P}{I}$

$\\ \rm\dashrightarrow V=\dfrac{0.4\times 10^3}{33\times 10^{-3}}$

$\\ \rm\dashrightarrow V=0.012\times 10^{-6}$

$\\ \rm\dashrightarrow V=12mV$

#2

$\\ \rm\dashrightarrow R=\rho \dfrac{\ell}{A}$

$\\ \rm\dashrightarrow \rho =\dfrac{RA}{\ell}$

$\\ \rm\dashrightarrow \rho=\dfrac{86.3(0.4\times 10^6)}{69}$

$\\ \rm\dashrightarrow \rho=0.5\times 10^{6}$

It should be silicon

#3

Ohms law

$\\ \rm\dashrightarrow R=\dfrac{V}{I}$

$\\ \rm\dashrightarrow R=\dfrac{7(10^3)}{6(10^{-6})}$

$\\ \rm\dashrightarrow R=1.167\times 10^9\Omega$

7 0

2 years ago

I need help on this question!!!

Irina-Kira [14]

2500
--------=3125
0.8

This can be can be viewed as compression due to the direction of the arrows.

7 0

3 years ago

1 A 75-g ball is projected from a height of 1.6 m with a horizontal velocity of 2 m/s and bounces from a 400-g smooth plate supp

Tanzania [10]

Answer with explanation:

We are given that

Mass of ball, $m_1=$ 75 g= $\frac{75}{1000}=0075kg$

1 kg=1000 g

Height, $h_1=1.6 m$

$h_2=0.6 m$

Horizontal velocity, $v_x=2 m/s$

Mass of plate $m_2=400 g=\frac{400}{1000}=0.4 kg$

a.Initial velocity of plate, $u_2=0$

Velocity before impact= $u_1=\sqrt{2gh_1}=\sqrt{2\times 9.8\times 1.6}=5.6m/s$

Where $g=9.8 m/s^2$

Velocity after impact, $v_1=\sqrt{2gh_2}=\sqrt{2\times 9.8\times 0.6}=3.4m/s$

According to law of conservation of momentum

$m_1u_1+m_2u_1=-m_1v_1+m_2v_2$

Substitute the values

$0.075\times 5.6+0=-0.075\times 3.4+0.4v_2$

$0.4v_2=0.075\times 5.6+0.075\times 3.4$

$v_2=\frac{0.075\times 5.6+0.075\times 3.4}{0.4}=1.69 m/s$

Velocity of plate=1.69 m/s

b.Initial energy= $\frac{1}{2}m_1v^2_x+m_1gh_1=\frac{1}{2}(0.075)(2^2)+0.075\times 9.8\times 1.6=1.326 J$

Final energy= $\frac{1}{2}m_1v^2_x+m_1gh_2+\frac{1}{2}m_2v^2_2$

Final energy= $\frac{1}{2}(0.075)(2^2)+0.075\times 9.8\times 0.6+\frac{1}{2}(0.4)(1.69)^2=1.162 J$

Energy lost due to compact=Initial energy-final energy=1.326-1.162=0.164 J

6 0

2 years ago

A 3047.8 kg truck has lost its brakes coming down a mountain. Fortunately, there is a ramp of thick gravel inclined at 9.5 degre

Yuliya22 [10]

Answer:

The work done by the gravel to stop the truck is 520.44 kJ

Explanation:

<u>Step 1</u>: Data given

Mass of the truck = 3047.8 kg

The ramp has an angle of 9.5 °

Velocity of the truck = 20.68 m/s

distance = 26.6 meters

<u>Step 2:</u> Calculate initial kinetic energy

sin 9.5° = 0.165

h = ℓ*sin 9.5° = 26.6*0.165= 4.39 m

Ek = 1/2m*Vo² = 1/2*3047.8*20.68² = 651714.7 Joule = 651.7 kJ = initial kinetic energy

<u>Step 3: </u>Calculate potential energy

Epot = U = m*g*h = 3047.8*9.81*4.39 = 131256.25 Joule = 131.26 kJ

<u>Step 4:</u> What work is done by the truck on the gravel?

Frictional energy Ef = 651.7 kJ - 131.26 kJ = 520.44 kJ

5 0

3 years ago

A child on a swing sweeps out a distance of 45 ft on the first pass. If she is allowed to continue swinging until she stops, an

earnstyle [38]

Answer:

d = 90 ft

Explanation:

Here in each swing the distance sweeps by the swing is half of the initial distance that it will move

So here we can say that total distance in whole motion is given as

$d = 45 + \frac{45}{2} + \frac{45}{4} + \frac{45}{8}..........$

since it is half of the distance that it will move in each swing so it would be a geometric progression with common ratio of 1/2

so sum of such GP is given by the formula

$S = \frac{a}{1 - r}$

$d = \frac{45}{1 - \frac{1}{2}}$

$d = 90 ft$

6 0

3 years ago