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3 years ago

Under what conditions is energy conserved

Physics

1 answer:

Alinara [238K]3 years ago

8 0

Answer:

If only internal forces are doing work (no work done by external forces), then there is no change in the total amount of mechanical energy. The total mechanical energy is said to be conserved. ... In these situations, the sum of the kinetic and potential energy is everywhere the same.

Explanation:

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An unknown radioactive element decays with a half life of 0.210 days. What is the decay constant, expressed in 1/microseconds, f

sergeinik [125]

The amount of a radioactive element over time can be written as:

$N=N_0e^{-\lambda t}$

So, considering that we know the time of its half life, we know how long it takes to get to half the original amount. This is (usint the amount of days in microseconds):

$0.5=1*e^{-\lambda *0.21*24*3600*10^6}\Rightarrow0.5=e^{-1.8144*10^{10}*\lambda}$ $ln(0.5)=-1.8144*10^{10}*\lambda\Rightarrow\lambda=\frac{ln(0.5)}{-1.8144*10^{10}}=3.82*10^{-11}$

Thus, lambda=3.82*10^(-11)/microseconds

3 0

1 year ago

S Problem Set 2.) 6.4 x 109 nm to cm

anyanavicka [17]

Answer:

$6.4\cdot 10^2 cm$

Explanation:

First of all, let's convert from nanometres to metres, keeping in mind that

$1 nm = 10^{-9} m$

So we have:

$6.4\cdot 10^9 nm \cdot 10^{-9} m/nm = 6.4 m$

Now we can convert from metres to centimetres, keeping in mind that

$1 m = 10^2 cm$

So, we find:

$6.4 m \cdot 10^2 cm/m = 6.4\cdot 10^2 cm$

8 0

3 years ago

Which type of motion most accurately describes the behavior of a friction -less pendulum?

kaheart [24]

Answer:

B) Periodic Motion

Explanation:

When a pendulum is friction-less, i.e there are no damping forces acting on it, its motion will be periodic, i.e it will bob up and down going from potential energy to kinetic energy and back. Thus, the motion of the pendulum can be best described by the term "period motion", hence choice B.

If however, forces do act on the pendulum, and if they acts as to damp the pendulum, it will oscillate less and less as time goes by, and eventually come to a stop (in the real world this damping force is usually air resistance ). And if the force acts in such a way that it increases the oscillations, the pendulum will swing higher and higher, and the system will go haywire! :)

4 0

4 years ago

Sound will travel slowest through which medium?

SSSSS [86.1K]

The speed of sound depends on the medium in which it is transported.

Sound travels fastest through solids, slower through liquids and slowest through gases.

So it will travel slowest through water at 55 degrees

8 0

4 years ago

Read 2 more answers

When an object accelerates, what about its motion changes? Question 1 options: Speed must change, but not velocity. Both speed a

QveST [7]

Answer:

The velocity must change but not speed.

Explanation:

Velocity is defined as the displacement by time. Whereas speed is expressed as the distance between two successive positions of the body to the time interval it took to travel.

Velocity, V = D / t m/s

Speed, s = d /t m/s

Velocity is a vector quantity that has a magnitude and direction.
The speed is a scalar quantity having only the magnitude.
At any instant of time, the magnitude of the velocity is always equal to the magnitude of the speed. The magnitude of velocity, |v | = magnitude of speed, |v |. The magnitude is always positive
The acceleration of a body is defined as the rate of change of velocity to time.

a = (v - u) / t m/s²

If a body is accelerating, It varies its velocity with respect to time.
In case of uniform circular motion, the speed remains constant, but the velocity changes continuously.

So, in the case of circular motion if an object accelerates, velocity must change but speed remains constant.

5 0

4 years ago