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4 years ago

PLEASE HELP ME!!!!! I'LL MARK YOU BRAINLIEST IF YOU ANSWER THIS CORRECTLY

Physics

2 answers:

mrs_skeptik [129]4 years ago

4 0

Answer: A

Explanation: Kinetic energy is when something is in motion so it would just make sense

Pachacha [2.7K]4 years ago

3 0

Answer: a

Explanation:

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A child bounces in a harness suspended from a door frame by three elastic bands. If each elastic band stretches 0.300 m while su

WINSTONCH [101]

Answer:

The force constant for each elastic band is 77.93 N/m

Explanation:

Hooke's law of a spring or an elastic band gives the relation between elastic force (Fe) and stretching (x), the magnitude of that force is:

$F_{e}= kx$ (1)

With k, the elastic force constant. The three elastic bands support the child’s weight (W) and maintain him at rest, so by Newton’s second law for one of the elastic bands:

$\sum F=0$ (2)

$\frac{W}{3}-F_{e}=0\Rightarrow F_{e}=\frac{W}{3}$ (3)

Using (1) on (3):

$kx=\frac{W}{3}\Rightarrow k=\frac{mg}{3x}$ (4)

$k=\frac{7.15\,kg*9.81\,\frac{m}{s^{2}}}{3*0.300\,m}\simeq\mathbf{77.93\frac{N}{m}}$

8 0

3 years ago

If v lies in the first quadrant and makes an angle Ï/3 with the positive x-axis and |v| = 4, find v in component form.

Alexeev081 [22]

Answer:

$v=$

Explanation:

We are given that

Magnitude of vector v= $\mid v\mid =4$

v lies in the first quadrant

$\theta=\frac{\pi}{3}$

$v_x=\mid v\mid cos\theta$

$v_y=\mid v\mid sin\theta$

Substitute the values then we get

$v_x=4cos\frac{\pi}{3}$

$v_x=4\times \frac{1}{2}=2$

$cos\frac{\pi}{3}=\frac{1}{2}$

$v_y=4\times sin\frac{\pi}{3}=4\times \frac{\sqrt 3}{2}=2\sqrt 3$

$sin\frac{\pi}{3}=\frac{\sqrt 3}{2}$

Therefore, the vector v in component form $=$

$v=$

4 0

4 years ago

The gravity tractor, is a proposed spacecraft that will fly close to an asteroid whose trajectory threatens to impact the Earth.

Crazy boy [7]

Answer:

$F_g=461lb_f$

Explanation:

First calculate the mass of the asteroid. To do so, you need to find the volume and know the density of iron.

If r = d/2 = 645ft, then:

$V = \frac{4}{3} \pi r^3$

$V = \frac{4}{3} \pi r^3\\V = 1.124\times10^{9}ft^3\delta_{iron}=m/V=491lb/ft^3m=V\times\delta=5.519\times10^{11}lb$

In order to find force, use Newton's universal law of gravitation:

$F_g=G\frac{m_1m_2}{d^2}$

Where,

G= the gravitational constant:

$G= 1.068846 \times10^{-9} ft^3 lb^{-1} s^{-2}$

$F_g=461lb_f$

4 0

3 years ago

A plane is travelling at 250km/h and must reach a target that is 3h 58min away. The distance to the target is. *

wariber [46]

Answer:

B) 89500 km

Explanation:

speed = distance / time

time= 3h 58 min = 30+58/60= 30.966 h = 31 hrs (approxx)

250= distance / 31

250× 31= distance

distance = 7750 ( approxx)

but none of the given options is 7750 km so we will choose the answer nearest to it,

therefore 89500km is the right answer

5 0

3 years ago

Who invented the first practical incandescent light bulb?.

OverLord2011 [107]

Answer:

Edison

Explanation:

Among other notable inventions, Edison and his assistants developed the first practical incandescent lightbulb in 1879 and a forerunner of the movie camera and projector in the late 1880s.

6 0

3 years ago