Is work being done on a barbell when a weight lifter is holding the barbell
over his head?

Answer:

0.196

Explanation:

According to Newton's second law

\sumFx = ma

Fm-Ff = ma

Fm is the moving force

Ff is the frictional force

m is the mass = 9kg

a is the acceleration = 2.4m/s²

Fm = Wsin theta

Fm = 9(9.8)sin25°

Fm = 37.28N

Ff is the frictional force = nmgcos theta

Ff = n(9)(9.8)cos25°

Ff = 79.94n

Substitute the given values into the formula

37.28-79.94n = 9(2.4)

-79.94n = 21.6-37.28

-79.94n = -15.68

n = 15.68/79.94

n = 0.196

Hence the coefficient of kinetic friction between the potted plant and the incline is 0.196

Option d...

Move more slowly........

When the temperature of a substance is lowered its particles move more slowly. Option d is correct. Temperature directs to the hotness or coldness of a body.

Temperature directs to the hotness or coldness of a body. In clear terms, it is the method of finding the kinetic energy of particles within an entity. Faster the motion of particles more the temperature.

Temperature is essential in all areas of Science right from Physics to Geology and also it is important in most parts of our everyday life.

As the temperature of a substance is lowered its particles move more slowly.

Hence Option d is correct.

To learn more about the temperature refer to the link;

https://brainly.com/question/7510619

Answer:

Now, think on the electrons flowing through a conductor (we can think on the resistor as a simple conductor, like a piece of metal)

Inside the conductor, we have some "fixed" (they do not flow with the current) electrons, such that as the current flows in the conductor, the flowing electrons can interact with the fixed ones in the conductor. Then we can have collisions inside the conductor.

In those collisions, the flowing electrons leave energy in the conductor, and as we know, heat is a form of energy. Then when we have a lot of these collisions, the temperature of the conductor increases.

That is why electronic devices get hot.

Also, as the temperature of a conductor increases, the electrons inside of it start to move more, then the probability of an interaction with the flowing electrons increases.

Answer:

Explanation:

The force acting on an object given it's mass and acceleration can be found by using the formula

force = mass × acceleration

From the question we have

force = 2000 × 3

We have the final answer as

Hope this helps you

Answer:

gases.

Explanation:

gases have the highest volume. if you compress (increase pressure) a gas, the volume decreases and it will take up less space as a liquid, and if you compress more, the liquid will become a solid.

additionally info: this is generally true, but as you get into more difficult subjects, this rule does not hold. for example, some substances cannot obtain a certain phase of matter when they are a certain temperature and or pressure. but that could be way more out of this questions league.

The given question is incomplete. The complete question is:

Estimate the volume of each ball. Use the formula [tex]v=\frac{4\pi\times r^3}{3}[/tex] where v is the volume and r is the radius. record the volume in table A of your student guide. The radius of the tennis ball is 2.1 cm and the radius of thr golf ball is 2.0 cm. What is the estimated volume of the table tennis ball in [tex]cm^3 [/tex] What is the estimated volume of the golf ball in

Answer: Volume of the tennis ball is [tex]38.8cm^3[/tex] and  Volume of the golf ball is [tex]33.5cm^3[/tex]

Explanation:

We have to find the Volume of tennis ball and golf ball by using the formula [tex]v=\frac{4\pi\times r^3}{3}[/tex]

Radius of the tennis ball = 2.1 cm

Radius  of the golf ball =2.0 cm.

Putting the value of radius in the formula , we get:

Volume of the tennis ball =  [tex]\frac{4\times 3.14\times (2.1cm)^3}{3} =38.8cm^3[/tex]

Volume of the golf ball =   [tex]\frac{4\times 3.14\times (2.0cm)^3}{3} =33.5cm^3[/tex]

Volume of the tennis ball is [tex]38.8cm^3[/tex] and  Volume of the golf ball is [tex]33.5cm^3[/tex]

it's  38.8 and 33.5 hope this helps

Answer:

3240000000 Joules

Explanation:

Answer:

The force of kinetic friction between the block and the floor is 2.4 N

Explanation:

The given parameters are;

The weight of the block = 8 Newtons

The velocity of the block = Constant velocity

Taking the kinetic friction for wood, [tex]\mu _k[/tex] = 0.3, we have;

The normal reaction of the block on horizontal ground, N = The weight of the block = 8 N

The force of kinetic friction between , [tex]F_k[/tex] = [tex]\mu _k[/tex] × N

Therefore, we have;

The force of kinetic friction between the block and the floor, [tex]F_k[/tex] = 0.3 × 8 N = 2.4 N.

Answer:

deuterium, helium and lithium

Explanation:

Big Bang nucleosynthesis is defined as the production of nuclei other than Hydrogen during the early phases of the universe but shortly after the occurrence of the Big Bang.

Now, the other nuclei formed are usually the elements deuterium, helium and lithium or their corresponding isotopes.

car moved 80 km to the South. What is its displacement? 80 km South -------------------------------------

Answer:

B. responsibility

Explanation:

Answer:

it appears to be B. acceleration

Answer: I believe the correct answer is A.

Answer:

Explanation:

Electric Bulb: In an electric bulb, the filament of bulb gives light because of heating effect of electricity. The filament of bulb is generally made of tungsten metal; having melting point equal to 3380°C.

Electric iron: The element of electric iron is made of alloys having high melting point. Electric heater and geyser work on the same mechanism.

Electric fuse: Electric fuse is used to protect the electric appliances from high voltage; if any. Electric fuse is made of metal or alloy of metals, such as aluminium, copper, iron, lead, etc. In the case of flow of higher voltage than specified, fuse wire melts and protects the electric appliances.

Answer:

Carbon Sink- photosythesis, ocean absorption, fossilization

Carbon Source- combustion, respiration

Explanation:

Answer:

Because in order for work to be done on an object, the object must be moving. Why isn't work being done on a barbell when a weight lifter is holding the barbell over his head? Work is maximized when force is applied in the same direction that the object is moving. ... In order to do work faster, more_is required.

Answer:

[tex]125\:\mathrm{minutes\: or\: }2.08\bar{3}\: \mathrm{hours}[/tex]

Explanation:

Speed is given by [tex]s=\frac{d}{t}[/tex], where [tex]d[/tex] is distance travelled and [tex]t[/tex] is time. Rearranging this equation, we have [tex]t=\frac{d}{s}[/tex].

Plugging in our given information:

[tex]t=\frac{d}{s}=\frac{1500\:\mathrm{km}}{720\:\mathrm{km/h}}=2.08\bar{3}\: \mathrm{hours}[/tex]

Thus, our answer is:

[tex]2.08\bar{3}\: \mathrm{hours}\cdot \frac{60\:\mathrm{minutes}}{1\:\mathrm{hour}}=\fbox{$125\:\mathrm{minutes}$}[/tex]

KE = 1000 J

Math

Pre-Algebra

Order of Operations: BPEMDAS

Physics

Energy

Kinetic Energy Formula: [tex]\displaystyle KE = \frac{1}{2}mv^2[/tex]

Step 1: Define

m = 20 kg

v = 10 m/s

Step 2: Find KE

Answer:

Position.

Explanation:

Motion can be defined as a change in location with respect to a reference point.

This ultimately implies that, motion would occur as a result of a change in location (position) of an object with respect to a reference point or frame of reference i.e where it was standing before the effect of an external force.

Mathematically, the motion of an object is described in terms of acceleration, time, distance, speed, velocity, displacement etc.

A complete description of your position includes a distance, direction, and reference point. Thus, this includes an object's distance in a certain direction from a reference point.

Answer:

C. Both a and b

Explanation:

Firstly, persons and objects in a moving plane as described in this question, are moving at the same speed as the plane even if there is no individual movement of these objects.

However, this question describes a person sitting still in a moving plane. This means that;

- The person is motionless in relation to everything in the plane i.e the person is not moving even if other things in the plane are.

- The person is in motion compared to everything on the ground i.e. the person is moving at the same speed as the plane, hence, in comparison with the ground, the person is moving.

Therefore, options A and B are correct

Answer:

[tex]\displaystyle V=7.5\ km/h[/tex]

Explanation:

Average Speed

If an object travels a distance d in a time t regardless of the direction, the average speed is the quotient of the distance over the time:

[tex]\displaystyle V=\frac{d}{t}[/tex]

It's known a person runs d=15 kilometers in t=2 hours, thus his/her average speed is:

[tex]\displaystyle V=\frac{15\ km}{2\ h}[/tex]

Calculating:

[tex]\boxed{\displaystyle V=7.5\ km/h}[/tex]

Answer:

An object at rest is described by Newton's First Law of Motion. An object in static equilibrium has zero net force acting upon it. The First Condition of Equilibrium is that the vector sum of all the forces acting on a body vanishes.

Explanation:

Answer:

see below

Explanation:

the first condition means that the light ray inside the optically denser medium hits the surface of the optically less dense medium.

this in simple words means, light must be travelling from am optically denser medium to an optically less dense medium

hope this helps :)

Answer:

F * t = m * Δv

F * t = m * (v2 - v1) where v2 is the new velocity and v1 is the current velocity

m * (v2 - v1) = (F * t)

Plugging in the values,

0.3kg * v2 - 0.3kg * 20 m/s = 5 * 0.03 s

0.3 * v2 - 6 = 0.15

0.3 * v2 = 0.15 + 6

v2 = 6.15 / 0.3

v2 = 20.5 m/s

The new velocity of motion is 20.5 m/s.

Answer:

6

Explanation:

From the given question, since a total of 12 V was obtained from the battery which is made up of a number of cells with each producing 2.0 V.

Assuming that the cells have a very low internal resistance, then;

minimum number of electric cells in the car battery = [tex]\frac{total voltage from the cells}{individual voltage of the cells}[/tex]

                                          = [tex]\frac{12}{2}[/tex]

                                          = 6

Thus, the minimum number of electric cells in the car battery is 6.

This implies that the addition of 6 cells which has 2.0 V supply in the battery produces a total of 12 V. Provided that the cells have a very low internal resistance.

Resistance is a material's tendency to resist the flow of charge (current). Resistance is the measure of the opposition to motion of free electrons(current) due to their continuous collisions with the atom of the lattice. An electric current flows when electrons move through a conductor, such as a metal wire. The moving electrons can collide with the atoms in the metal. This makes it more difficult for the current to flow, and causes resistance. The unit of Resistance is "OHM". Ohm is denoted by the greek letter "Ω".

  If a current 'I' is caused to flow in a conductor by a battery of potential difference 'V', it is found that the current is directly proportional to potential difference provided there is no change in the conductor itself. That means more will be I if we increase V. So

                     [tex]{\Longrightarrow}\qquad \qquad \qquad I {\propto} V\\\\{\Longrightarrow}\qquad \qquad \qquad I = KV[/tex]

Where K is Conductance. Conductance is the ability of a conductor to allow the current to pass through it.  Resistance(R) is the reciprocal(opposite) of conductance(K) thus K is inversely proportional to R,

                     [tex]{\Longrightarrow}\qquad \qquad \qquad I = \frac{1}{R}V \\\\{\Longrightarrow}\qquad \qquad \qquad V = IR[/tex]

This is known as OHM's Law, and V = IR is the equation linking the R, V and I.

[tex]\Huge\text{Circuit Diagram:}[/tex]

Circuit Diagram no 1 attached is of this question. In the circuit diagram, V is voltmeter to find the potential difference, A is the ammeter to find the current, R is the resistance i.e. the conductor wire, The switch and the battery.

Suppose the wire of length 100 cm is connected to a battery, the Voltmeter observes the potential difference and ammeter reads the current of the wire. We will use the R, V and I i.e. V = IR equation to find out the resistance of that wire and Record the resistance. Then attach another small wire of suppose 90 cm to the battery, and similarly Find out its resistance too. After recording the resistance 3 or 4 times, you will observe that When you decrease the length of the wire,

The resistance of a conductor depends upon the following factors.

                   [tex]{\Longrightarrow}\qquad \qquad \qquad R\quad {\propto}\quad L[/tex]    

                   [tex]{\Longrightarrow}\qquad \qquad \qquad R\quad {\propto}\quad \frac{1}{A}[/tex]

The relation between only length of the wire and resistance is [tex]R\quad {\propto} \quad L[/tex] . The relation of R, L and A is given by, ρ

                    [tex]{\Longrightarrow}\qquad \qquad \qquad R\quad {\propto}\quad \frac{L}{A}\\\\{\Longrightarrow}\qquad \qquad \qquad R\quad =\ \frac{\ {\rho}\ L\ }{A}[/tex]

Where ρ is known as resistivity depends upon the nature of the material of the wire. The meter of resistivity is Ω x m(Ohm x meter).

[tex]\Huge\text{I-V Characteristic:}[/tex]

I-V curves of an electrical device or component, are a set of graphical curves which are used to define its operation within an electrical circuit. I-V characteristic curves show the relationship between the current flowing through an electronic device and the applied voltage across its terminals. The circuit diagram to find I-V characteristic must have a resistor which is a device or component connected to a battery which is providing the potential difference V. When a resistor is connected to a battery, current I is observed due to drift velocity. To find the current and potential difference(voltage) the circuit must have the Ammeter and voltmeter. Recorded current and voltage must be used to plot the graph to check the I-V characteristic. The picture attached is the circuit diagram.

We calculate the resistance at constant temperature by ohm's law. The Ohms law is applied at constant temperature because the resistance of any material varies with the change in temperature. It shows a linear relationship between the applied voltage and the resulting current, resistance being a constant. So we could use V = IR because resistance is constant at constant temperature.

Answer:

An object moves with constant velocity .

Explanation:

•2nd law

Answer:

92 OHMS

Explanation:

The resistance will be "92 ohm".

According to the question,

Current,

Voltage,

As we know the formula,

→ [tex]I = \frac{V}{R}[/tex]

or,

→ [tex]R = \frac{V}{I}[/tex]

By substituting the values, we get

→     [tex]= \frac{230}{2.5}[/tex]

→     [tex]= 92 \ ohm[/tex]

Thus the answer above is right.

Learn more:

https://brainly.com/question/16841137