C.
It is a motion with uniform acceleration, meaning that the acceleration will not change.
The object is thrown upwards with a positive velocity. This shows that the upward direction is positive. The object will decelerate due to gravity at a magnitude of 9.81 m/s2. Therefore, the acceleration is -9.81 m/s2.
Note that even though the velocity of the object is momentarily 0 m/s at maximum height, there is still a constant acceleration.
This allows the object first decelerate upwards, then change direction at max height, and finally accelerate downwards. So in this case, the acceleration is always negative and unchanged.

7 0

3 years ago

A resistor with r = 340 ω and an inductor are connected in series across an ac source that has voltage amplitude 490 v. The rate

Arada [10]

The value of impedance Z of the circuit, when the rate at which electrical energy is dissipated in the resistor is 316 w, is 508 ohms.

<h3>What is impedance Z of the circuit?</h3>

The impedance Z of the circuit is the ratio of voltage amplitude to the maximum current.

$Z=\dfrac{V}{I}$

Here, <em>V </em>is voltage amplitude and<em> I</em> maximum current.

A resistor with R = 300 Ω and an inductor are connected in series across an ac source that has voltage amplitude 490V. The rate at which electrical energy is dissipated in the resistor is 316 W.

The rate at which electrical energy is dissipated in the resistor is the product of the resistance and the square of current. Thus,

$316=340\times I^2\\I=\sqrt{\dfrac{316}{340}}\\I=0.964\rm\; A$

The impedance Z of the circuit is,

$Z=\dfrac{V}{I}\\Z=\dfrac{490}{0.964}\\Z=508\rm\; ohm$

Thus, the value of impedance Z of the circuit, when the rate at which electrical energy is dissipated in the resistor is 316 w, is 508 ohms.

Learn more about the impedance Z of the circuit here:

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5 0

2 years ago

Science is hard sometimes help please!

dolphi86 [110]

Yeah science is hard. Hopefully you do good in it :)

8 0

3 years ago

A crane lifts up two boxes.<br><br> Which free body diagram shows the forces acting on block A?

Temka [501]

Answer:

The 3rd graph

Explanation:

A free body diagram is a diagram which shows all the forces acting on an object.

The problem asks us to find the free body diagram of block A, so we must find all the forces acting on block A.

We have 3 forces acting on block A in total:

- The force of gravity (its weight), which pushes the block downward (in the diagram, it is the force represented with $F_{gA}$

- The tension in the rope 1, which pulls block A upwards: this force is represented with $F_{T1}$

- The tension in the rope 2, due to the weight of block 2, which pulls block A downwards: this force is represented with $F_{T2}$

Based on the direction of these 3 forces, the correct diagram is the 3rd one.

7 0

3 years ago

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