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Y_Kistochka [10]
3 years ago
10

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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A block and tackle is used to lift an automobile engine that weighs 1800 N. The person exerts a force of 300 N to lift the engin
Sidana [21]

Answer:

1800/300 = 6ropes

Explanation:

The engine weighs 1800N and the person exerts a force of 300N, so for him to lift the engine and exerting a force of 300N all through we divide the weight of the engine by the force exerted to know how many ropes are used. Which makes it 6 thereby each rope uses 300N to lift the engine.

8 0
4 years ago
A car is traveling with a constant speed when the driver suddenly applies the brakes, giving the 14) car a deceleration of 3.50
sergij07 [2.7K]
To be able to determine the original speed of the car, we use kinematic equations to relate the acceleration, distance and the original speed of the car moving. 

First, we manipulate the one of the kinematic equations
 
v^2 = v0^2 + 2 (a) (x)  where v = 0 since the car stopped

Writing the equation in such a way that the initial velocity or v0 is written on one side of the equation,

<span>we get v0 = sqrt (2(a)(x))

Substituting the known values,

v0 = sqrt(2(3.50)(30.0))
v0 = 14.49 m/s 
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Therefore, before stopping the car the original speed of the car would be 14.49 m/s
7 0
4 years ago
The voltage applied across a given parallel-plate capacitor is doubled. How is the energy stored in the capacitor affected?
ikadub [295]

Answer:

The energy stored in the capacitor quadruples its original value.

Explanation:

The energy stored in a capacitor is given by the equation

U=\frac{1}{2}CV^2

where

C is the capacitance

V is the voltage across the plates

The capacitance, C, depends only on the properties of the capacitor, so it does not change when the voltage applied is changed.

Instead, in this problem the voltage applied is doubled:

V' = 2V

So the new energy stored is

U'=\frac{1}{2}C(2V)^2=4(\frac{1}{2}CV^2)=4U

so, the energy stored has quadrupled.

8 0
3 years ago
which of the following is true in regard to a charged atom? a. when an atom loses an electron, it becomes an anion, which is neg
3241004551 [841]
<span>Among the choices provide, the one statement that is true with regards to a charged atom is C, the number of protons and the number of electrons within the same atom are unequal. A charged atom is called an ion. Atoms are nonpartisan since they have similar quantities of positive and negative charges.</span>
8 0
4 years ago
Read 2 more answers
A child of mass M is swinging on a swing set. The ropes attaching the swing to the top bar have length L. Find the gravitational
myrzilka [38]

Answer:

(a) 0

(b) 10ML

(c) 10ML(1 - cos(\theta))

(d) 10ML(1 + sin(\phi))

Explanation:

(a) When hanging straight down. The child is at the lowest position. His potential energy with respect to this point would also be 0.

(b) Since the rope has length L m. When the rope is horizontal, he is at L (m) high with respect to the lowest swinging position. His potential energy with respect to this point should be

E_h = mgh = 10ML

where g = 10m/s2 is the gravitational acceleration.

(c) At angle \theta from the vertical. Vertically speaking, the child should be at a distance of Lcos(\theta) to the swinging point, and a vertical distance of L - Lcos(\theta) to the lowest position. His potential energy to this point would be:

E_{\theta} = mgh = 10M(L - Lcos(\theta)) = 10ML(1 - cos(\theta))

(d) at angle \phi from the horizontal. Suppose he is higher than the horizontal line. This would mean he's at a vertical distance of Lsin(\phi) from the swinging point and higher than it. Therefore his vertical distance to the lowest point is L + Lsin(\phi) = L(1 + sin(\phi))

His potential energy to his point would be:

E_{\phi} = mgh = 10ML(1 + sin(\phi))

5 0
4 years ago
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