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2 years ago

14

The half-life of a radioisotope is 6.0 hours. Approximately how long will it take for the activity of a sample to be reduced by

98%?

1 answer:

DerKrebs [107]2 years ago

3 0

Answer:

1 hours will be the best answer

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Consider a parachutist that has reached terminal velocity. which of the following is true? A.) The acceleration of the parachuti

trasher [3.6K]

The correct answer is:
<span>B.) At terminal velocity there is no net force

In fact, when the parachutist reaches the terminal velocity, his velocity does not change any more. It means that the acceleration acting on the parachutist is zero, and for Newton's second law, this means the net force acting on him is zero:
</span> $\sum F = ma = 0$
<span>because the acceleration is zero: a=0.
This also means that the two relevant forces acting on the parachutist (gravity, downward, and air resistance, upward) are balanced to produce a net force equal to zero.</span>

8 0

3 years ago

The distance between 4 nodes (3 sections, 2 sections= wavelength) is 15.0cm. The frequency of the source is 10Hz. What's the spe

Natalija [7]

Answer:

the speed of the waves is 150 cm/s

Explanation:

Given;

frequency of the wave, f = 10 Hz = 10

distance between 4 nodes, L = 15.0 cm

The wavelength (λ) of the wave is calculated as follows;

Node to Node = λ/2

L = 2(Node to Node) = (4 Nodes) = 2 (λ/2) = λ

Thus, λ = L = 15.0 cm

The speed (v) of the wave is calculated as follows;

v = fλ

v = 10 Hz x 15.0 cm

v = 150 cm/s

Therefore, the speed of the waves is 150 cm/s

7 0

2 years ago

Explain numericals of electricity chapter of class 10 and also diagrams.What is ammeter?What is voltmeter?potential difference?O

SVEN [57.7K]

Let's explain the following electrical terms.

• Electric current, can be said to be the flow of electric charge. These charges are through a conductor by moving electrons.

• Ammeter, is an instrument used to measure the amount of electric current in a circuit.

The name ammeter was derived from the unit of electric current (Amperes).

• Voltmeter, can be said to be an instrument used to measure the voltage(potential difference) in a circuit. It measures the electric potential between two points in an electrical circuit. It can also be called voltage meter.

• Electric circuit, can be defined as the conductive path for the flow of electric current.

It allows electric charge carriers to flow continuously.

• Resistance ,can be said to be the property of an electrical conductor which resists the flow of electric current. It is measured in ohms.

• Ohms law, states that the potential difference (V) between two points is directly proportional to the electric current across two points.

It is deonted as: V = I x R

Voltage = Current x Resistance

• Electric potential ,can be said to be the amount of electric potential energy at a point.

3 0

1 year ago

In which of these samples do the molecules most likely have the most kinetic energy? (2 points)

Vinvika [58]

D, water vapor. Gaseous state would have more kinetic energy, they are moving faster. If you have to compare the same state, then higher temperature would have the higher kinetic energy. But if you have solid and liquid at the same temperature - then liquid would have more.

4 0

3 years ago

A rock with density 1900 kg/m3 is suspended from the lower end of a light string. When the rock is in air, the tension in the st

wel

Answer:

the tension T2 when the rock is completely immersed is T2 = 29.05 N

Explanation:

from Newton's second law

F= m*a

where F= force , m= mass , a= acceleration

when the rock is suspended ,a=0 since it is at rest. Then

T1 - m*g = 0 , T1= tension when suspended in air , g= gravity

assuming constant density of the rock

m= ρ rock *V , where ρ rock = density of the rock , V= volume

thus

T1= m*g = ρ rock *g*V

V= T1/(ρ rock *g)

when the rock is submerged in oil , it receives an upward force that equals the weight of the volume of displaced oil (V displaced). Since it is completely submerged the volume displaced is the volume of the rock V=Vdisplaced

When the rock is at rest , then

F= m*a=0

T2 + ρ oil *g*V displaced - ρ rock *g*V =0

T2 = ρ rock *g*V - ρ oil *g*V = g*V (ρ rock - ρ oil)

T2 = g*V (ρ rock - ρ oil) = T1/(ρ rock *g) *g * (ρ rock - ρ oil)

T2 = T1 * (ρ rock - ρ oil)/ρ rock

replacing values

T2 = 48 N * (1900 kg/m3- 750 kg/m3)/ 1900 kg/m3 = 29.05 N

T2 = 29.05 N

3 0

3 years ago