A main sequence star cools and expands. It must be entering which stage?

1 answer:

4 0

If a main sequence star is cooling and expanding, it is entering the red giant stage. This means that the star has burned up all of it's hydrogen and is now starting to burn its helium making it cooler.

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Slow moving vehicles that travel at a speed less than ___ mph will have an orange reflective triangle with red around the edges

nika2105 [10]

Slow moving vehicles that travel at a sped less than 25 MPH will have ...........
Slow moving vechicles [SMV] are those vehicles that travel on the road at a speed that is less than the recommended speed, example of a slow moving vehicle is tractor. These vehicles must have SMV signs on them to notify other drivers that they would not be travel fast.

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2 years ago

A bullet of mass 10g is fired from a gun. The bullet takes 0.003s to move through its barrel and leaves it with a velocity of 30

dsp73

Answer:

1,000 N

Explanation:

$v=300 \text{ms}^{-1} ;u=0,t=000.3\text{s},m=0.01\text{kg}$

Force exerted by the bullet on the rifle = $\frac{m(v-u)}{\text{time}}$

F = 1000N

Contextual Way:

Newton's second law of motion.

F=m a

Now to solve based on the current info, we shall assume that:-

The force exerted on the bullet was uniform across the entire duration of bullet leaving the barrel, i.e., 0.003 seconds {Not necessarily true for real life applications as the force will not be uniform from the point of hammer impact till the point of leaving the barrel. In reality you will get a Force profile across that entire duration}

We are not distinguishing between bullet and cartridge. {What you shall hold in your hand and load in a revolver is a cartridge containing the gunpowder, bullet etc. The bullet is the projectile at the mouth of the cartridge that actually leaves the barrel and hit the target. So when you are weighing in real life, you are not weighing the bullet, rather the cartridge as a whole}

Getting back to the question

Impulse equation for the bullet

∫F∗dt=∫m∗dv

Average impulse delivered= Change in momentum of the bullet

Assuming average force delivery

Favg∗∫dt=m∗∫dv

Favg∗0.003=0.010∗300

Favg=300∗10/3

Favg=1000N

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1 year ago

A man 6 feet tall walks at a rate of 6 feet per second away from a light that is 15 feet above the ground.