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3 years ago

I'm stuck on number 4... help please?

Physics

2 answers:

lora16 [44]3 years ago

8 0

$V= \frac{\Delta S}{\Delta t} = \frac{5}{15} = \frac{1}{3} m/s$

Paha777 [63]3 years ago

3 0

Average <u>speed</u> = (distance covered) / (time to cover the distance) =

   (5m) / (15 sec) =

   (5/15) (m/s) = <em>1/3 m/s</em> .

Average <u>velocity</u> =

   (displacement) / (time spent traveling) in the direction of the displacement

Average velocity = (5m) / (15 sec) left =

   (5/15) / (m/sec) left =

   <em>1/3 m/s left</em>.

A number without a direction is a speed, not a velocity.

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miskamm [114]

Answer:

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4 years ago

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You see the boy next door trying to push a crate down the sidewalk. He can barely keep it moving, and his feet occasionally slip

Murrr4er [49]

Answer:

Explanation:

Given that the weight of the crate is

M=48kg

Then, weight of boy is

W=mg=48×9.8=470.4N

ΣF = ma ,Along y axis

Since the body is not moving in y direction then, a=0 along y axis

N-W=0

N=W

The normal equals weight of boy

N=470.4N

Then, applying frictional force opposing the boy motion.

Fr=μN

Fr=0.5×470.4

Fr=235.2N

Then, this is the forward force that the boy try using to pull the crate.

Since he can barely move his foot he has not yet overcome the coefficient of static friction.

ΣF = ma. , along x-axis

a along x-axis is 0 since he cannot move his foot, I.e he was not moving

F-Fr= 0

F=Fr=235.2N

The forward force the boy apply is 235.2N on the crate

Also, analysing the crate.

The forward force is now F=235.2N

Then the frictional force =Fr

Then,

ΣF = ma. , along x-axis

a along x-axis is 0 since the crate did not move,

F-Fr=0

Fr=F=235.2N

This is the frictional force on the crate.

Then using frictional law

Fr=μN

N=Fr/μ

N=235.2/0.9

N=261.33N

Now this normal is equal to the weight of the crate

ΣF = ma ,Along y axis

Since the body is not moving in y direction then, a=0 along y axis

N-W=0

W=N=261.33N

Then, since weight is given as

W=mg

m=W/g

m=261.33/9.81

m=26.64kg

The mass of the crate is 26.64kg

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3 years ago

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A 290-turn solenoid having a length of 32 cm and a diameter of 11 cm carries a current of 0.30 A. Calculate the magnitude of the

iris [78.8K]

The magnitude of the magnetic field inside the solenoid is 3.4×10^(-4) T.

To find the answer, we need to know about the magnetic field inside the solenoid.

<h3>What's the expression of magnetic field inside a solenoid?</h3>

Mathematically, the expression of magnetic field inside the solenoid= μ₀×n×I

n = no. of turns per unit length and I = current through the solenoid

<h3>What's is the magnetic field inside the solenoid here?</h3>

Here, n = 290/32cm or 290/0.32 = 906

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Thus, we can conclude that the magnitude of the magnetic field inside the solenoid is 3.4×10^(-4) T.

Learn more about the magnetic field inside the solenoid here:

brainly.com/question/22814970

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2 years ago

Approximately how long are fossil fuels going to last (at the present level of consumption)?

Murljashka [212]

Answer:

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Globally, we currently consume the equivalent of over 11 billion tonnes of oil from fossil fuels every year. Crude oil reserves are vanishing at a rate of more than 4 billion tonnes a year, so if we carry on as we are, our known oil deposits could run out in just about 50 years.

Gas

If we increase gas production to fill the energy gap left by oil, our known gas reserves only give us just 52 years left.

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Although it’s often claimed that we have enough coal to last hundreds of years, this doesn’t take into account the need for increased production if we run out of oil and gas.

If we step up production to make up for depleted oil and gas reserves, our known coal deposits could be gone in 114 years.

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The answer would be B

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