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3 years ago

A car traveling at 28 m/s starts to decelerate steadily. It comes to a complete stop in 13 seconds. What is its acceleration?

Physics

1 answer:

Maru [420]3 years ago

5 0

Acceleration = (change in speed) / (time for the change)

change in speed = (speed at the end) minus (speed at the beginning)

change in speed = (zero) minus (28 m/s) = -28 m/s

Acceleration = (-28 m/s) / (13 sec)

Acceleration = -2.15 m/s²

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3 years ago

A sample has a density of 30 g/ml. there is 60 ml of this substance.how much does it weigh?

aleksandrvk [35]

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3 years ago

A mixture of helium and oxygen is used in scuba diving tanks to help prevent ""the bends"". 46 L helium and 12 L oxygen are comb

marin [14]

Answer

given,

For helium

Volume,V = 46 L

Pressure,P = 1 atm

Temperature,T = 25°C = 273 +25 = 298 K

R=0.0821 L . atm /mole.K

n₁ = ?

number of moles

we know

P V = n R T

$n_1 =\dfrac{46 \times 1}{0.0821\times 298}$

n₁ = 1.89 moles

For oxygen

Volume,V = 12 L

Pressure,P = 1 atm

Temperature,T = 25°C = 273 +25 = 298 K

R=0.0821 L . atm /mole.K

n₂ = ?

number of moles

we know

P V = n R T

$n_2 =\dfrac{12 \times 1}{0.0821\times 298}$

n₂ = 0.49 moles

Total volume of tank = 5 L

temperature of tank = 298 K

Partial pressure of helium

$P_1=\dfrac{n_1 R T}{V}$

$P_1=\dfrac{1.89\times 0.0821\times 298}{5}$

P₁ = 9.25 atm

Partial pressure of oxygen

$P_2=\dfrac{n_2 R T}{V}$

$P_2=\dfrac{0.49\times 0.0821\times 298}{5}$

P₂ = 2.39 atm

total pressure

P = P₁ + P₂

P = 9.25 + 2.39

P = 11.64 atm

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3 years ago

A 60 kg skydiver is falling at a terminal velocity of 50 m/s.

marishachu [46]

Answer:

The gravitational force is definitely acting downwards towards the ground and this is equal to the weight of the skydiver.

the acceleration a = 7.8 m/s²

Explanation:

Given that :

the mass of the skydiver = 60 kg

Velocity = 50 m/s

Thus; gravitational force is definitely acting downwards towards the ground and this is equal to the weight of the skydiver.

Also; the air resistance is acting upward and the resultant of both forces = mass×acceleration

So;

mg-R = ma

60(9.8) - 120 = 60(a)

588 -120 = 60a

468 = 60a

a = $\frac{468}{60}$

a = 7.8 m/s²

Hence, the acceleration a = 7.8 m/s²

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3 years ago

Which describes the process of conduction?

fenix001 [56]

I think the correct answer from the choices listed above is option A. The process of conduction is described by the heat energy is transferred from the land to the air by direct contact. Conduction is the process of heat transfer that happens through the collisions between molecules.

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3 years ago