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3 years ago

A sample of a radioactive substance is reduced to 1.0 gram after 4 half-lives. Determine the mass of the original sample

Physics

1 answer:

luda_lava [24]3 years ago

6 0

After 4 half-lives, there was 1 gram.

1 half-life earlier, after 3 half-lives, there must have been 2 grams.

1 half-life earlier, after 2 half-lives, there must have been 4 grams.

1 half-life earlier, after 1 half-life, there must have been 8 grams.

1 half-life earlier, when it started decaying, there must have been 16 grams. <em>(B) </em>

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Compare and contrast fluorescent and incandescent light bulbs.

dezoksy [38]

Incandescent light is a glowing white light produced by heat. An incandescent light bulb works by heating a filament in the bulb. Fluorescent light is a bright light produced by electricity flowing through a tube filled with ionized gas. Fluorescent light bulbs are more energy-efficient than incandescent bulbs

5 0

3 years ago

After driving a portion of the route, the taptap is fully loaded with a total of 27 people including the driver, with an average

lara [203]

Answer:

compression of spring is x = 0.12 m

Assumed k = 160,000 N/m ........ Truck's suspension system

Explanation:

Given:

- The mass of average person m_p = 69 kg

- Total number of persons n_p = 27

- The mass of each goat m_g = 15 kg

- The total number of goats n_g = 3

- The mass of each chicken m_c = 3 kg

- The total number of goats n_c = 5

- The total mass of bananas m_b = 25 kg

Find:

How much are the springs compressed?

Solution:

- Using equilibrium equation on the taptap in vertical direction:

F_net = F_spring - F_weight = 0

- Compute the force due to all the weights on the taptap:

F_weight = (n_p*m_p + n_g*m_g + n_c*m_c + m_b)*9.81

F_weight = (69*27 + 3*15 + 5*3 + 25)*9.81

F_weight = 19109.88 N

- The restoring force of a spring is given by:

F_spring = k*x

Where, k is the spring stiffness and x is the displacement:

F_weight = F_spring

19109.88 = k*x

x = 19109.88 / k

We need to assume the spring stiffness we will take k = 160,0000 N/m (trucks suspension systems). The value of the stiffness must be high enough to sustain a load of 1.911 tonnes.

x = 19109.88 / 160,000

x = 0.1194 m ≈ 0.12 m = 12 cm

- A compression of 12 cm seems reasonable for a taptap to carry 1.911 tonnes of load. Hence, the assumption of spring stiffness was reasonable. Hence, the compression of spring is x = 0.12 m.

8 0

3 years ago

Scientists studying an anomalous magnetic field find that it is inducing a circular electric field in a plane perpendicular to t

bija089 [108]

This question is incomplete, the complete question is;

Scientists studying an anomalous magnetic field find that it is inducing a circular electric field in a plane perpendicular to the magnetic field. The electric field strength 1.5 m from the center of the circle is 7 mV/m.

At what rate is the magnetic field changing?

Answer:

the magnetic field changing at the rate of 9.33 m T/s

Explanation:

Given the data in the question;

Electric field E = 7 mV/m

radius r = 1.5 m

Now, from Faraday law of induction;

∫E.dl = d∅/dt

E∫dl = A( dB/dt )

E( 2πr ) = πr² ( dB/dt )

( 0.007 ) = (r/2) ( dB/dt )

( 0.007 ) = 0.75 ( dB/dt )

dB/dt = 0.007 / 0.75

dB/dt = 0.00933 T/s

dB/dt = ( 0.00933 × 1000) m T/s

dB/dt = 9.33 m T/s

Therefore, the magnetic field changing at the rate of 9.33 m T/s

5 0

3 years ago

An airplane with an airspeed of 120 km/h has a heading of 30 degree east of North in a wind that is blowing toward the east at 6

lesya692 [45]

Answer:

Explanation:

Velocity of plane relative to ground V_pg = ?

Given the velocity in vector form ,

velocity of plane relative to air V_pw = 120 cos30 i + 120sin30j

V_wg = 60 i

V_pg = V_pw +V_wg

= 120 cos30 i + 120sin30j + 60i

= 164 i + 60 j

magnitude

=251 km / h

8 0

3 years ago

In an elastic collision, a 580 kg bumper car collides directly from behind with a second, identical bumper car that is traveling

kozerog [31]

Answer: vl = 2.75 m/s vt = 1.5 m/s

Explanation:

If we assume that no external forces act during the collision, total momentum must be conserved.

If both cars are identical and also the drivers have the same mass, we can write the following:

m (vi1 + vi2) = m (vf1 + vf2) (1)

The sum of the initial speeds must be equal to the sum of the final ones.

If we are told that kinetic energy must be conserved also, simplifying, we can write:

vi1² + vi2² = vf1² + vf2² (2)

The only condition that satisfies (1) and (2) simultaneously is the one in which both masses exchange speeds, so we can write:

vf1 = vi2 and vf2 = vi1

If we call v1 to the speed of the leading car, and v2 to the trailing one, we can finally put the following:

vf1 = 2.75 m/s vf2 = 1.5 m/s

8 0

3 years ago