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2 years ago

9

PLS HELP I NEED THIS BY TODAY

1 answer:

Margaret [11]2 years ago

8 0

I would say the answer is A

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If kinetic energy of a body is decreased by 10percent then decrease in linear momentum of that body

algol [13]

Answer:

E = 1/2 M V^2 = 1/2 P V since P = M V

E2 / E1 = P2 V2 / (P1 V1)

P2 / P1 = E2 V1 / (E1 V2) = V2^2 V1 / (V1^2 V2) = V2 / V1

E2 / E1 = V2^2 / V1^2

V2 / V1 = (E2 / E1)^1/2

V2 / V1 = (.9)1/2 = .95

The linear momentum would have to decrease by 5%

7 0

2 years ago

A train travels 59 kilometers in 3 hours, and then 74 kilometers in 5 hours. What is its average speed?

dybincka [34]

Average speed = (total distance) / (total time)

Total distance = 59 km + 74 km = 133 km

Total time = 3 hrs + 5 hrs = 8 hrs

Average speed = (133 km) / (8 hrs) = 16.625 km/hr

3 0

2 years ago

A sledge hammer has a mass of 4.0 kg and is moving at a speed of 6.0m/s when it strikes a fence post, driving it 10 cm further i

Afina-wow [57]

Part a)

kinetic energy of the hammer will be

$KE = \frac{1}{2} mv^2$

here we know that

m = 4 kg

v = 6 m/s

now by the equation of kinetic energy we have

$KE = \frac{1}{2}*4 * 6*6$

$KE = 72 J$

Part b)

for finding the force we will have

$v_f^2 - v_i^2 = 2 a d$

here we know that

$v_f = 0$

$v_i = 6 m/s$

$d = 10 cm = 0.10 m$

now from above equation we have

$0 - 6^2 = 2 * a * 0.10$

$a = -180 m/s^2$

now by Newton's II law we have

$F = ma$

$F = 4*180 = 720 N$

so it requires 720 N.

8 0

3 years ago

A mass of 100 g stretches a spring 5 cm. If the mass is set in motion from its equilibrium position with a downward velocity of

garri49 [273]

Answer:

$w_{0}=14$

$t=\frac{\pi }{14}$

Explanation:

<u>Data</u>

<u>mass m= 100g</u>

<u>Length L= 5cm</u>

<u>we can use:</u>

<u>gm-kL= 0</u>

<u>divide both side by m</u>

<u>g - </u> $\frac{kL}{m}$ <u>=0</u>

<u>where</u>

$\frac{k}{m}$ = $\frac{g}{L}$

$\frac{k}{m}=w_{0}$ ^{2}

so now

$w_{0}^{2}$ = $\frac{9.8*100}{5}$

$w_{0}^{2}=\frac{980}{5}$

$w_{0}^{2}=196$

square both side

$w_{0}=\sqrt{196}$

$w_{0}=14$

We can apply:

u(t)=Acoswt +Bsinwt

u(t)=Acos14t +Bsin14t

u(0)=0 where A=0

therefore

u(0) = Bsin14t

$u^{'}$ (0) = 10 ⇒ 10=14B ⇒ B= $\frac{14}{10}$ B= $\frac{5}{7}$

so now u(t)= $\frac{5}{7}$ sin14t

so t will be:

t= $\frac{\pi }{14}$

t= $\frac{3.14}{14}$

t=0.22 seconds

8 0

3 years ago

Complete the passage to describe the relationship between intensity and loudness. Intensity is the amount of ______ that flows i

Usimov [2.4K]

Answer:

Blank One: I'm not certain but I'd assume it's either sound or energy.

Blank Two: Louder

Explanation:

volume is controlled by how much energy is put in an area per a unit of time, so the more energy in one area for a unit of time, the louder the sound will come out.

Sorry I couldn't give the best explanation!

7 0

2 years ago

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