PHYSICS HIGH SCHOOL

A student throws a 5.0-newton ball straight up.What is the net force on the ball at its maximum
height?
(1) 0.0 N (3) 5.0 N, down
(2) 5.0 N, up (4) 9.8 N, down

Answers

Answer 1
Answer:
If the ball weighs 5 newtons, then that's the force of gravity that
attracts it to the center of the Earth.  The force only depends on
the mass of the ball and its distance from the center of the Earth. 
The force of gravity doesn't care whether the ball is moving or at
rest. It doesn't change significantly until the ball moves to some
significant distance off the Earth's surface, which isn't happening
if it's tossed by a human being. 

So we have a downward force of 5 newtons on the ball at all times.
In order to find the net force on it, we have to identify any other
forces besides gravity that are also acting on it.

If the ball were moving through the air, then there would be a force
of air resistance on it, acting opposite to its motion. But when it's
at its maximum height, in the process of turning around from rising
to falling, there's an instant when it's not moving through the air at all,
so gravity is the only force acting on it. At that moment, the net force
on the ball is 5.0 newtons downward.

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What is the momentum of an object at rest, in m/s?

Answers


Momentum = (mass) x (speed)

If the speed is zero, then the momentum is zero.

What is meant by fundamental unit? write any two difference between mass and weight.​

Answers

Answer:

Fundamental unit is any unit that is not dependent on other units and other units can be derived from them

Explanation:

Units such as Kilogram, Mass and Time are said to be fundamental units because they are independent.

Differences between Mass and weight;

1. Mass is the measure of the amount of matter in a body while weight is a measure of how the force of gravity acts upon that mass.

2. Mass is a scalar quantity while weight is a vector quantity

A body of mass 2 kg is moving in the positive X-Direction with a speed of 4 m/s collides head on with an another body of mass 3 kg moving in the negative X-Direction with a speed of 1 m/s . During collision a loud sound is heard and they both start moving together . the sound energy cannot be greater than :A) 12 J
B) 14 J
C) 15 J
D) 17.5 J

Answers

m_1=2 \n m_2=3 \n v_1=4 \n v_2=1 \n v\text{ =speed after collision (to be determined)}.

The momentul of the system preserves:

m_1v_1-m_2v_2=(m_1+m_2)v \ \ \ \ \ \Rightarrow \ \ \ \ \ v=(m_1v_1-m_2v_2)/(m_1+m_2).

Ok, we found the speed after the collision.
Now, because the impact is plastic, it produces heat, sound energy and who knows what other forms of energy. We denote all this wasted energy with E.

Now, we write the energy conservation law:

(m_1v_1^2)/(2)+(m_2v^2_2)/(2)=((m_1+m_2)v^2)/(2)+E

From the above equation, you find E,  and then conclude that the sound energy can certainly not be greater than this.

Lead has a density of 11.3 g/cm3 and a mass of 282.5 g. What is its volume?

Answers

Well we know that density=mass divided by volume, so let's substitute :)

11.3=282.5/V

Now we know that 282.5 has to be divided by SOMETHING in order to get 11.3.

You can waste time trying every number under the sun, or you can use a little trick I learned in elementary school which is to divide 282.5 by 11.3. This works because it shows how many times 11.3 goes into 282.5 which is the volume of this "piece of" lead. Since 11.3 goes perfectly 25 times into 282.5, the Volume of this "piece of" lead is 25 cm³. :)

All nuclear energy results in the rapid release of energy, such as in atomic bombs. a. True
b. False

Answers

It is true that all nuclear energy results inthe rapid release of energy, such as in atomic bombs. A process wherein the atom’s nucleusis further divided into two nuclei, that is, fission products, is callednuclear fission. This happens when the nuclei of radioactive elements (e.g.Uranium or Plutonium isotopes) are able to attract neutrons. Because theseisotopes’ nuclei are unstable, an addition to their energy causes them todivide into new pieces of neutron. In nuclear reactors, fission occurs when thepower plant gathers heat from a steam in a physical process. Nuclear reactorsare designed to sustain nuclear chain reactions.

Answer:

FALSE

Explanation:

verified answer***

Nuclear energy is released from an atom through one of two processes: nuclear fusion or nuclear fission. In nuclear fusion, energy is released when the nuclei of atoms are combined or fused together. But isn't rapidly release

If 105 J of energy is used in 103 s, what is the average power consumption in watts?

Answers

Given : 105 J (Work)
             103 s (time)

Unknown: P=?
Formula: P=W/t
Solution: P= 105 J/103 s = n

Answer: P= 1.02 J/s or watts is the average power
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