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IRISSAK [1]
3 years ago
13

What element is used as a source of radiation in smoke detectors?

Physics
1 answer:
mart [117]3 years ago
4 0
Americium ( A source of alpha radiation to detect and identify smoke.)
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a 5.0 kg ball is dropped from a 2.5 m high window. what is the velocity of the ball just before it hits the ground?
julsineya [31]

Answer:

Approximately 7.0\; \rm m \cdot s^{-1}.

Assumption: the ball dropped with no initial velocity, and that the air resistance on this ball is negligible.

Explanation:

Assume the air resistance on the ball is negligible. Because of gravity, the ball should accelerate downwards at a constant g = 9.81 \; \rm m \cdot s^{-2} near the surface of the earth.

For an object that is accelerating constantly,

v^2 - u^2 = 2\, a \, x,

where

  • u is the initial velocity of the object,
  • v is the final velocity of the object.
  • a is its acceleration, and
  • x is its displacement.

In this case, x is the same as the change in the ball's height: x = 2.5\; \rm m. By assumption, this ball was dropped with no initial velocity. As a result, u = 0. Since the ball is accelerating due to gravity, a = 9.81\; \rm m \cdot s^{-2}.

v^2 - u^2 = 2\, g \cdot h.

In this case, v would be the velocity of the ball just before it hits the ground. Solve for

v^2 = 2\, a\, x + u^2.

\begin{aligned}v &= \sqrt{2\, a\, x + u^2} \\ &= \sqrt{2\times 9.81 \times 2.5 + 0} \\ &\approx 7.0\; \rm m\cdot s^{-1}\end{aligned}.

3 0
2 years ago
A diagram of a closed circuit with a power source on the left labeled 120 V. There are 3 resistors in parallel, separate paths,
Zina [86]

1) The equivalent resistance is 2.73\Omega

2) The voltage in the circuit is 120 V

3) The total current in the circuit is 44.0 A

Explanation:

1)

Resistors are said to be in parallel when they have the same potential difference at their terminals.

The formula to calculate the equivalent resistance for three resistors in parallel is:

\frac{1}{R_T}=\frac{1}{R_1}+\frac{1}{R_2}+\frac{1}{R_3}

where R_1, R_2, R_3 are the resistances of the three resistors.

In this problem, the resistance of each resistor is:

R_1 = 5.0 \Omega

R_2 = 10.0 \Omega

R_3 = 15.0 \Omega

Substituting,

\frac{1}{R_T}=\frac{1}{5}+\frac{1}{10}+\frac{1}{15}=\frac{11}{30}

So the equivalent resistance is

R_T = \frac{30}{11}=2.73 \Omega

2)

In this problem we are told that the three resistors are connected in parallel. This means that their terminals are connected to the same point of the circuit: therefore, this means that they also have the same potential difference across them.

Therefore, the voltage in each branch containing each resistor is the same, and it is equal to the voltage of the battery, which is

V=120 V

So, the voltage in the circuit is 120 V.

3)

The total current in the circuit can be found by using Ohm's law:

V=RI

where

V is the voltage

R is the equivalent resistance of the circuit

I is the current

In this circuit, we have:

V = 120 V

R=2.73\Omega

Re-arranging the equation for I, we find the current:

I=\frac{V}{R}=\frac{120}{2.73}=44.0 A

Learn more about current and potential difference:

brainly.com/question/4438943

brainly.com/question/10597501

brainly.com/question/12246020

#LearnwithBrainly

4 0
3 years ago
Read 2 more answers
The rate of turn at any airspeed is dependent upon
bagirrra123 [75]

Answer:

the rate of turn at any airspeed is dependent upon the horizontal lift component

6 0
2 years ago
A long, straight, horizontal wire carries a left-to-right current of 40 A. If the wire is placed in a uniform magnetic field of
sladkih [1.3K]

Answer:

The magnitude of the resultant of the magnetic field is 4.11\times10^{-5}\ T

Explanation:

Given that,

Current = 40 A

Magnetic field B=3.7\times10^{-5}\ T

Distance = 22 cm

We need to calculate the magnetic field

Using formula of magnetic field

B'=\dfrac{\mu_{0}I}{2\pi r}

Where, r = distance

I = current

Put the value into the formula

B'=\dfrac{4\pi\times10^{-7}\times20}{2\pi\times0.22}

B'=1.8\times10^{-5}\ T

We need to calculate the magnitude of the resultant of the magnetic field

Using formula of resultant

B''=\sqrt{B^2+B'^2}

Put the value into the formula

B''=\sqrt{(3.7\times10^{-5})^2+(1.8\times10^{-5})^2}

B''=4.11\times10^{-5}\ T

Hence, The magnitude of the resultant of the magnetic field is 4.11\times10^{-5}\ T

6 0
3 years ago
What is the weight of an astronaut who has a mass of 90 kg on the moon? (Note: acceleration due to gravity of the moon is 1.62 N
motikmotik

Answer:

W = 145.8 [N]

Explanation:

To solve this problem we must remember that weight is defined as the product of mass by gravity, in this case lunar gravity.

W = m*g

where:

m = mass = 90 [kg]

g = gravity acceleration = 1.62 [kg/m²]

W = 90*1.62

W = 145.8 [N]

8 0
3 years ago
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