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3 years ago

Can a light bulb work without energy transfer.

1 answer:

6 0

Answer:Energy cannot be created or destroyed. It can be stored, or it can be transferred i.e. from a hot object to a cool object by conduction, convection or radiation.

Explanation:

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Scientists use what scale to compare the hardness of minerals?

frozen [14]

Mohs hardness scale. hope this helps

4 0

3 years ago

Balanced forces act on a ball that is being held above the ground in someone's hand. explain why these forces on the ball are ba

Licemer1 [7]

Hi Andrescruz9386

The ball in someone's hand is a balanced force because the object is staying in motion and is not changing at all so its evenly balanced, if its swinging back and fourth it is in motion and it wont stop till it becomes unbalanced, if the ball is just being held above the ground yes its balanced because nothing Is happening to it, its basically like a balance scale, if both sides are even and equal, than nothing will happen because there is no side that has more or less its equal so that's why its balanced, in order for it to be unbalanced it has to be brought upon unbalanced forces.

3 0

3 years ago

Please help me with this (with explanation)

Sergeeva-Olga [200]

Suppose the cyclist travels for a total time of t hours.

For 20 min = 1/3 hr, the cyclist does not move.

Over the remaining (t - 1/3) hr, the cyclist is moving at a constant speed of 22.0 km/hr, so that the cyclist would travel a distance of

x = (22.0 km/hr) • ((t - 1/3) hr) ≈ (22.0 km/hr) t - 7.33 km

If the cyclist's average speed over the total time t was 17.5 km/hr, then by the definition of average speed,

17.5 km/hr = x / t

Replace x with the distance expression from earlier:

17.5 km/hr = ((22.0 km/hr) t - 7.33 km) / t

Solve for t :

17.5 km/hr = 22.0 km/hr - (7.33 km) / t

(7.33 km) / t = 4.5 km/hr

t = (7.33 km) / (4.5 km/hr)

t ≈ 1.62963 hr

Then the distance the cyclist traveled must have been

x ≈ (22.0 km/hr) (1.62963 hr) - 7.33 km ≈ 28.5 km

and so the answer is A.

Alternatively, as soon as you arrive at

17.5 km/hr = x / t

you can instead solve for t in terms of x, then plug that into the distance equation.

t = x / (17.5 km/hr)

then

x ≈ (22.0 km/hr) (x / (17.5 km/hr)) - 7.33 km

x ≈ 1.25714 x - 7.33 km

0.25714x ≈ 7.33 km

x = (7.33 km) / 0.25714 ≈ 28.5 km

6 0

3 years ago

Suppose that the voltage across the resistor is held constant at 40 volts. If the resistance is steadily decreasing at a rate of

hjlf

Answer:

The current is increasing at a rate of 0.32 ampere per second.

Explanation:

The voltage of the resistor is modelled after Ohm's Law, which states that voltage is directly proportional to current:

$V = i\cdot R$ (1)

Where:

$V$ - Voltage, measured in volts.

$i$ - Current, measured in amperes.

$R$ - Resistance, measured in ohms.

An expression for the rate of change in voltage is found by Differential Calculus:

$\frac{dV}{dt} = \frac{di}{dt}\cdot R +i\cdot \frac{dR}{dt}$

$\frac{dV}{dt} = \frac{di}{dt}\cdot R + \frac{V}{R}\cdot \frac{dR}{dt}$ (2)

Where:

$\frac{dV}{dt}$ - Rate of change in voltage, measured in volts per second.

$\frac{di}{dt}$ - Rate of change in current, measured in amperes per second.

$\frac{dR}{dt}$ - Rate of change in resistance, measured in ohms per second.

If we know that $\frac{dV}{dt} = 0\,\frac{V}{s}$ , $R = 5\,\Omega$ , $V = 40\,\Omega$ and $\frac{dR}{dt} = -0.2\,\frac{\Omega}{s}$ , then the rate of change in current is: