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3 years ago

______ states that energy cannot be created or destroyed.

Physics

2 answers:

Alex3 years ago

7 0

Answer:

c. The law of conservation of energy

Explanation:

The famous "law of conservation of Energy" states that energy inside an isolated system remains conserved. It can not be created and can't be destroyed as well. The energy can only be moved or transformed into another form.

This can be proved using "Noether's Theorem". Classically, only energy was considered conserved but Special Relativity proved that even mass is conserved as it showed the relation between mass and energy.

Pavel [41]3 years ago

4 0

The answer is a newton second law

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A car sitting at a red light begins to accelerate at 2.0 m/s2 when the light turns green. It continues with this acceleration un

KonstantinChe [14]

Answer:

$d = 820 m$

Explanation:

here we know that car starts from rest and continue to accelerate till it will reach to maximum speed of 20 m/s

so we will have

$v_f - v_i = at$

$20 - 0 = 2t$

$t = 10 s$

so car will accelerate till t = 10 then it will move with uniform speed

so the distance moved by the car till it accelerates is given as

$d = \frac{1}{2}at^2$

$d = \frac{1}{2}(2)(10^2)$

$d_1 = 100 m$

now it will move with uniform speed for next 36 s

so we have

$d_2 = 20(36) = 720 m$

so total distance moved by the car is given as

$d = d_1 + d_2$

$d = 100 + 720$

$d = 820 m$

8 0

3 years ago

A police siren of frequency fsiren is attached to a vibrating platform. The platform and siren oscillate up and down in simple h

babunello [35]

Answer:

he maximum frequency occurs when the denominator is minimum

f’= f₀ $\frac{343}{343 + v_s}$

Explanation:

This is a doppler effect exercise, where the sound source is moving

f = fo $\frac{v}{v-v)s}$ when the source moves towards the observer

f ’=f_o $\frac{v}{v+v_{sy}}$ Alexandrian source of the observer

the maximum frequency occurs when the denominator is minimum, for both it is the point of maximum approach of the two objects

f’= f₀ $\frac{343}{343 + v_s}$

8 0

3 years ago

When asked how to create an electromagnet, the best answer would be:

fredd [130]

Answer:

You can create an electromagnet by wrapping an insulated wire around a metal with ferromagnetic properties and applying an electric current."

Explanation:

Electromagnets are made by wrapping an insulated wire around a metal with ferromagnetic properties (example is iron), to form a loop, and then applying a current through the wire. Electromagnets can generate magnetism with a strong force field, and unlike normal magnets, their strength can be varied by varying the amount of current flowing through the coil. Their main disadvantage, which is also their most utilized property is that their magnetism is lost once the current flowing through the wire is cut-off.

4 0

3 years ago

Your friends sit in a sled in the snow. If you apply a force pf 75 N to them, they have an acceleration of 0.9 m/s ^ 2. What is

Elza [17]

Answer:

Mass of the sled in the snow 83.33 kg.

<u>Explanation</u>:

Given that,

Force applied to move the sled in the snow (F) = 75N

$\text { Acceleration }(a)=0.9 \mathrm{m} / \mathrm{s}^{2}$

We know that

Newton's second law of motion is

$\text { Force }=\text { mass } \times \text { acceleration }$

F = ma (Or "force" is equal to "mass" times "acceleration".)

So if we move this around we can isolate mass and get mass

$\text { Mass }=\frac{\text { force }}{\text { accelearation }}$

$\mathrm{M}=\frac{75}{0.9}$

M = 83.33 kg

Mass of the sled in the snow <u>83.33 kg.</u>

3 0

3 years ago

At an instant a traffic light turns green an automobile that has been waiting at an intersection of the road accelerates with 5m

joja [24]

1) The car overtakes the truck at a distance of 160 m far from the intersection.

2) The velocity of the car is 40 m/s

Explanation:

The car is travelling with a constant acceleration starting from rest, so its position at time t (measured taking the intersection as the origin) is given by

$x_c(t) = \frac{1}{2}at^2$