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3 years ago

The ball is partially white, is that an observation or an inference??

Physics

1 answer:

fenix001 [56]3 years ago

4 0

Answer:

this is an observation.

Explanation:

you are observing that the ball is partially white

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In a 5000 m race, the athletes run 12 1/2 laps; each lap is 400 m.Kara runs the race at a constant pace and finishes in 17.9 min

Ksju [112]

Answer:

No. of laps of Hannah are 7 (approx).

Solution:

According to the question:

The total distance to be covered, D = 5000 m

The distance for each lap, x = 400 m

Time taken by Kara, $t_{K} = 17.9 min = 17.9\times 60 = 1074 s$

Time taken by Hannah, $t_{H} = 15.3 min = 15.3\times 60 = 918 s$

Now, the speed of Kara and Hannah can be calculated respectively as:

$v_{K} = \frac{D}{t_{K}} = \frac{5000}{1074} = 4.65 m/s$

$v_{H} = \frac{D}{t_{H}} = \frac{5000}{918} = 5.45 m/s$

Time taken in each lap is given by:

$(v_{H} - v_{K})t = x$

$(5.45 - 4.65)\times t = 400$

$t = \frac{400}{0.8}$

t = 500 s

So, Distance covered by Hannah in 't' sec is given by:

$d_{H} = v_{H}\times t$

$d_{H} = 5.45\times 500 = 2725 m$

No. of laps taken by Hannah when she passes Kara:

$n_{H} = \frac{d_{H}}{x}$

$n_{H} = \frac{2725}{400} = 6.8$ ≈ 7 laps

3 0

3 years ago

A large box sits on a rough floor. A person pushes on the box with a horizontal force of magnitude 50 N. The box remains at rest

artcher [175]

Answer:

The magnitude of the frictional force is $F_f \ge 50 \ N$

Explanation:

From the question we are told that

The force exerted on the box is $F = 50 \ N$

Generally for the box to remain at rest then it means that the frictional force is greater than or equal to the force applied to move it i.e

$F_f \ge F$

=> $F_f \ge 50 \ N$

5 0

3 years ago

A TMS (transcranial magnetic stimulation) device creates very rapidly changing magnetic fields. The field near a typical pulsed-

GrogVix [38]

Explanation:

It is given that, the field near a typical pulsed-field machine rises from 0 T to 2.5 T in 200 μs

Change in magnetic field, $dB=2.5\ T$

Change in time, $dt=200\ \mu s=200\times 10^{-6}\ s=2\times 10^{-4}\ s$

Diameter, d = 2.3 cm

Radius, r = 0.0115 m

Emf is induced in the ring as the field changes. It is given by :

$E=\dfrac{d\phi}{dt}$

$E=\dfrac{d(B.A\ cos(0))}{dt}$

$E=A\dfrac{d(B)}{dt}$

$E=\pi (0.0115)^2\dfrac{2.5}{2\times 10^{-4}}$

E = 5.19 volts

So, the emf induced in the ring is 5.19 volts. Hence, this is the required solution.

5 0

4 years ago

True or false A radioactive isotope that can be followed through the steps of a chemical reaction is an indicator.

ozzi

Hi, your answer is false.

I hoped I helped and if you need more you could always ask me :)

-Dawn

6 0

3 years ago

Mutations can be transmitted to the next generation only if they are present in

emmainna [20.7K]

Answer:

The germline (the gametes)

Explanation:

Mutations are permanent changes in the DNA sequence. They can occur randomly, from mistakes during DNA replication, or as the result of external factors like UV radiation.

For these mutations to be passed on to the next generation, they must be present in the DNA of the gametes(i.e. the egg and sperm cells). This is because this is the DNA that goes on to make the offspring in the next generation following fertilisation.

If mutations are present in somatic cells (i.e. cells other than the gametes), they are not passed on to the next generation. For example, if someone gets mutations in their skin cells as a result of exposure to UV rays, this will not be passed on to their children.

7 0

3 years ago