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3 years ago

A closed system consists of a pendulum that is swinging back and forth. If

Physics

2 answers:

Zigmanuir [339]3 years ago

4 0

Answer:

answer: its gravitational potential energy must increase

Explanation:

this was right for the test i am currently taking, but please be weary that we could be taking different tests. plz dont hate me if its wrong :c

Mashcka [7]3 years ago

3 0

Answer:

The correct choice is D. Its gravitational potential energy must increase

Explanation:

Conservation of Mechanical Energy

The total amount of mechanical energy, in a closed system in the absence of dissipative forces like friction or air resistance, remains constant.

This means that energy cannot disappear or appear and that potential energy can become kinetic energy or vice versa.

In a closed system like a pendulum, two types of energies are considered: Gravitational potential (U) and kinetic (K). Thus, the sum of both energies must remain constant in time.

Suppose the pendulum is at a state where U=150 J, and K=350 J. The total mechanical energy is:

M = 150 J + 350 J = 500 J

If the kinetic energy decreases to a new value, say K = 200 J, then the gravitational potential must increase to compensate for this new condition, that is: U = 300 J

The correct choice is D. Its gravitational potential energy must increase

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Please help! A net force of 2.0 N acts on a 2.0-kg object for 10 seconds. What is the object’s kinetic energy after that 10 seco

padilas [110]

For Newton's second law, the force F applied to the object of mass m will cause an acceleration a of the body:
$F=ma$
So, the acceleration is
$a= \frac{F}{m}= \frac{2.0 N}{2.0 kg}=1 m/s^2$

The object undergoes through this acceleration for 10 seconds, t=10 s. Since it is an accelerated motion, we can find its final velocity after 10 seconds:
$v_f = v_i + at=0 m/s+(1m/s^2)(10 s)=10 m/s$
where $v_i$ is the initial velocity of the object, which is zero since it starts from rest.

Finally we can calculate the final kinetic energy of the object, which is given by
$K= \frac{1}{2}mv^2= \frac{1}{2}(2.0 kg)(10 m/s)^2=100 J$

7 0

3 years ago

Pls help it's due today

mario62 [17]

Answer:

Breh seriously. Ugh fine.

1.B

2.D

3.C

4.C

5.D,A and B

6.A,C and D

3 0

2 years ago

An empty oﬃce chair is at rest on a ﬂoor. Consider the following forces:. 1. A downward force due to gravity;. 2. An upward forc

LenaWriter [7]

The forces acting on the chair are:

4. 1 and 2 only.

6 0

3 years ago

Read 2 more answers

You and your friend Peter are putting new shingles on a roof pitched at 20°. You're sitting on the very top of the roof when Pet

dexar [7]

Answer:

vi = 3.95 m/s

Explanation:

We can apply the Work-Energy Theorem as follows:

W = ΔE = Ef - Ei

W = - Ff*d

then

Ef - Ei = - Ff*d  

Ei = Ki + Ui = 0.5*m*vi² + m*g*hi = 0.5*m*vi² + m*g*hi = m*(0.5*vi² + g*hi)

hi = d*Sin 20º = 5.1 m * Sin 20º = 1.7443 m

Ef = Kf + Uf = 0 + 0 = 0

As we know, vf = 0 ⇒ Kf = 0

Uf = 0 since hf = 0

we get

W = ΔE = Ef - Ei = 0 - m*(0.5*vi² + g*hi) ⇒ W = - m*(0.5*vi² + g*hi)  (I)

W = - Ff*d = - μ*N*d = - μ*(m*g*Cos 20º)*d = - μ*m*g*Cos 20º*d (II)

we can say that

- m*(0.5*vi² + g*hi) = - μ*m*g*Cos 20º*d

⇒ vi = √(2*g*(μ*Cos 20º*d - hi))

⇒ vi = √(2*(9.81 m/s2)*(0.53*Cos 20º*5.1m - 1.7443 m)) = 3.95 m/s

6 0

3 years ago

A train travels 8.81 m/s in a -51.0° direction. The train accelerated for 2.23 s, changing its velocity to 9.66 m/s in a 37.0° d

Evgen [1.6K]

The value of the $\rm \triangle x$ will be 29.14 m. Delta represent the change.

<h3>What is velocity?</h3>

The change of distance with respect to time is defined as speed. Speed is a scalar quantity. It is a time-based component. Its unit is m/sec.

The velocity in the part 1;

V₁ = 8.81

The velocity in the part 2;

V₂ = 9.66 m/sec

The resultant of the two vectors of velocity gives the velocity for the connecting path.

$\rm V = \sqrt{8.81 ^2 + 9.66^2 } \\\\ V= 13.07 \ m/sec$

The time period for the train accelerates;

$\rm \triangle x = v \times t \\\\ \triangle x = 13.07 \ m/sec \times 2.23 \ sec \\\\ \triangle x = 29.14 \ m$

Hence the value of the $\rm \triangle x$ will be 29.14 m.

To learn more about the velocity, refer to the link: brainly.com/question/862972.

#SPJ1

7 0

2 years ago