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s2008m [1.1K]
3 years ago
5

What is the half-life of this radioactive isotope that decreases to one-fourth its original amount in 18 months?

Physics
1 answer:
o-na [289]3 years ago
4 0
The half-life of this radioactive isotope is 9 months for it decreases to one-fourth its original amount in 18 months. Half-life means a certain length of time after which half of the amount of radioactive element has decayed.
Therefore, the half-life of this particular isotope is 18 months. After 18 months the isotope was at one-half, then another 18 months, the isotope was at one-fourth, which is 9 months where one-fourth is one-half of one half.  
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A ball is falling at terminal velocity. Terminal velocity occurs when the ball is in equilibrium and the forces are balanced. Wh
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Answer:

A free body diagram with 2 forces: the first pointing downward labeled F Subscript g Baseline 20 N and the second pointing upward labeled F Subscript air Baseline 20 N.

Explanation:

This is because at terminal velocity, the ball stops accelerating and the net force on the ball is zero. For the net force to be zero, equal and opposite forces must act on the ball, so that their resultant force is zero. That is F₁ + F₂ = 0 ⇒ F₁ = -F₂

Since F₁ = 20 N, then F₂ = -F₁ = -20 N

So, if F₁ points upwards since it is positive, then F₂ points downwards since it is negative.

So, a free body diagram with 2 forces: the first pointing downward labeled F Subscript g Baseline 20 N and the second pointing upward labeled F Subscript air Baseline 20 N best describes the ball falling at terminal velocity.

4 0
3 years ago
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What determines the path that an object in projectile motion follows
Ilia_Sergeevich [38]
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A ball of radius r rolls on the inside of a track of radius R. If the ball starts from rest at the vertical edge of the track, f
meriva

Answer:

v=\sqrt{\dfrac{10g(R-r)}{7}}

Explanation:

Given that

Radius of track = R

Radius of ball = r

The ball can be treated as solid sphere, so

The moment of inertia of ball

I=\dfrac{2}{5}mr^2

When the ball reach at the lowest position then it will have both angular and linear speed.

Condition for  rolling without slipping       v= ωr

Form energy conservation

mgR=mgr+\dfrac{1}{2}mv^2+\dfrac{1}{2}I\omega^2

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I=\dfrac{2}{5}mr^2

mgR=mgr+\dfrac{1}{2}mv^2+\dfrac{1}{2}\times \dfrac{2}{5}mr^2\omega^2

mg(R-r)=\dfrac{1}{2}mv^2+\dfrac{1}{2}\times \dfrac{2}{5}mv^2

2mg(R-r)=mv^2+\dfrac{2}{5}mv^2

2g(R-r)=\dfrac{7}{5}v^2

v=\sqrt{\dfrac{10g(R-r)}{7}}

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Sergio039 [100]
I really hope this could help u

7 0
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The Sun is to a planet as -
serg [7]

Answer:a

Explanation:

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