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3 years ago

How does friction act as an unbalanced force for objects in motion?

1 answer:

8 0

Friction is a force that acts in a direction opposite to motion. If there were not force of friction, a baseball player would never stop and would be continuously moving in the direction of motion. Balanced forces do not cause a nonmoving object to start moving.

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A student examines the effect of the number of D batteries in a closed circuit on the brightness of a light bulb. In the experim

xxTIMURxx [149]

Answer:

Placing cells in series increases the

voltage in the circuit by 1.5 V for each

cell. Increasing the voltage increases the

brightness of the bulb

Explanation:

I. MAKING THE CONNECTION

How many terminals are located on the battery? 2

How many terminals are located on the bulb? 2

II. PLACING CELLS IN SERIES

What is the effect on the brightness of the bulb by increasing the number of cells?

The bulbs become brighter when increasing the number of cells.

What changes occur in the current in the circuit when increasing the number of cells?

Increasing the number of cells increases the current in the circuit.

What changes occur in the voltage in the circuit when increasing the number of cells?

Increasing the number of cells increases the voltage (for cells in series the voltage is additive).

What changes occur in the resistance in the circuit when increasing the number of cells?

The resistance is determined by the number of bulbs. The resistance in the circuit remains unchanged.

III. PLACING BULBS IN SERIES

What is the effect on the brightness of the bulbs by increasing the number of bulbs?

Increasing the number of bulbs decreases the brightness of the bulbs.

What changes occur in the resistance in the circuit as more bulbs are added?

The resistance increases. In a series circuit, adding bulbs increases the resistance in the circuit.

What changes occur in the current in the circuit as more bulbs are added?

Increasing the resistance decreases the current.

Observations on unscrewing one bulb. Explain your observations.

A complete circuit requires the electrons to move from the negative terminal of the battery to the

positive terminal. When one bulb is unscrewed it opens the circuit preventing a complete circuit and

the electrons cannot return to the battery.

IV. PLACING BULBS IN PARALLEL

Compare the brightness with two bulbs in parallel with two bulbs in series.

Two bulbs in parallel are brighter than two bulbs in series.

How does increasing the number of circuits (bulbs) change the current and resistance?

In a parallel circuit each bulb is in its own circuit. As bulbs are added the resistance in the circuit

decreases since each circuit is another pathway for electrons to move from one end of the circuit

4 0

4 years ago

Work output of a large machine in a factory is 89,000 joules, and it’s input is 102,000 joules. Work output of a similar machine

mojhsa [17]

(89000/102000)×100
=87.25%

(92000/104000)×100
=88.46%

efficiency is (output/input)×100
if u get confused which way input and output should go, remember the smaller value is always output and it's above in the fraction, then only it's possible to get a efficiency lower than 100.

7 0

3 years ago

Read 2 more answers

When the cylinder is displaced slightly along its vertical axis it will oscillate about its equilibrium position with a frequenc

Nesterboy [21]

Answer:

w = √[g /L (½ r²/L2 + 2/3 ) ]

When the mass of the cylinder changes if its external dimensions do not change the angular velocity DOES NOT CHANGE

Explanation:

We can simulate this system as a physical pendulum, which is a pendulum with a distributed mass, in this case the angular velocity is

w² = mg d / I

In this case, the distance d to the pivot point of half the length (L) of the cylinder, which we consider long and narrow

d = L / 2

The moment of inertia of a cylinder with respect to an axis at the end we can use the parallel axes theorem, it is approximately equal to that of a long bar plus the moment of inertia of the center of mass of the cylinder, this is tabulated

I = ¼ m r2 + ⅓ m L2

I = m (¼ r2 + ⅓ L2)

now let's use the concept of density to calculate the mass of the system

ρ = m / V

m = ρ V

the volume of a cylinder is

V = π r² L

m = ρ π r² L

let's substitute

w² = m g (L / 2) / m (¼ r² + ⅓ L²)

w² = g L / (½ r² + 2/3 L²)

L >> r

w = √[g /L (½ r²/L2 + 2/3 ) ]

When the mass of the cylinder changes if its external dimensions do not change the angular velocity DOES NOT CHANGE

4 0

4 years ago

The author’s feeling about a subject or topic, which is evidenced in word choice, is called __________.

MatroZZZ [7]

The author’s feeling about a subject or topic, which is evidenced in word choice, is called tone. <span>They could be literal meanings which are meanings explicitly given to the readers or the person being told to. In this type of meaning, the person doesn’t need to think the words too much or ponder on the meaning because they could easily understand what the other person or the author implies. Meanwhile connotative meanings are meanings using different figures of speech or symbolism that the person still needs to think it over before knowing the actual meaning of the word, sentence or story.</span>

5 0

4 years ago

Read 2 more answers

A conducting sphere is charged up such that the potential on its surface is 100 V (relative to infinity). If the sphere's radius

Klio2033 [76]

Answer: the potental with twice larger radius 0.5* Vo ( being Vo =100V)

Explanation: In order to solve this proble, we know that teh potential due to charged sphere relative V=0 at infinity, we have

Vo=k*Q/R where R is the sphere radius

if we enlarge the radius to 2R the

V= k*Q/2*R = Vo/2

3 0

4 years ago