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3 years ago

A scientific study is repeated by four different groups. Only two groups get the same results. Are the data reproducible?

Physics

1 answer:

tangare [24]3 years ago

4 0

No, one more group must get the same result as the other group. This will make it more reliable and reproducible.

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AN airplane travels 4000 m in 20s on a heading 0f 35 degrees north west. Calculate average velocity .

alexandr402 [8]

Isn't velocity Distance over time? if the degree isn't adding resistance it should be 4000 ÷ 20 which gives you 200mps ("per second") which is the velocity without resistance.

6 0

3 years ago

"On a movie set, an alien spacecraft is to be lifted to a height of 32.0 m for use in a scene. The 260.0-kg spacecraft is attach

Lisa [10]

Answer:

The time interval required to lift the spacecraft to this specified height is 123.94 seconds

Explanation:

Height through which the spacecraft is to be lifted = 32.0 m

Mass of the spacecraft = 260.0 kg

Four crew member each pull with a power of 135 W

18.0% of the mechanical energy is lost to friction.

work done in this situation is proportional to the mechanical energy used to move the spacecraft up

work done = (weight of spacecraft) x (the height through which it is lifted)

but the weight of spacecraft = mg

where m is the mass,

and g is acceleration due to gravity 9.81 m/s

weight of spacecraft = 260 x 9.81 = 2550.6 N

work done on the space craft = weight x height

==> work = 2550.6 x 32 = 81619.2 J

this is equal to the mechanical energy delivered to the system

18.0% of this mechanical energy delivered to the pulley is lost to friction.

this means that

0.18 x 81619.2 = 14691.456 J is lost to friction.

Total useful mechanical energy = 81619.2 J - 14691.456 J = 66927.74 J

Total power delivered by the crew to do this work = 135 x 4 = 540 W

But we know tat power is the rate at which work is done i.e

$P = \frac{w}{t}$

where p is the power

where w is the useful work done

t is the time taken to do this work

imputing values, we'll have

540 = 66927.74/t

t = 66927.74/540

time taken t = 123.94 seconds

8 0

3 years ago

an aircraft has a liftoff speed of 53 m/s. what is the minimum constant acceleration an airplane must have to reach that takeoff

xxMikexx [17]

Answer:

$a=3.34\ m/s^2$

Explanation:

Accelerated Motion

It refers to the motion of objects in which velocity is not constant over time. If the change of the velocity occurs at the same rate, then we say it's uniformly accelerated. Being $v_o$ = initial speed, $v_f$ = final speed, a= constant acceleration, x= distance traveled

Then, the scalar relation between them is

$v_f^2=v_o^2+2ax$

The aircraft needs to reach a liftoff speed of 53 m/s from rest (assumed) having only 420 meters to do so. We can compute the acceleration by solving for a

$\displaystyle a=\frac{v_f^2-v_0^2}{2x}$