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2 years ago

A cross-country skier travels 40 meters north in 2 minutes. What is the skiers velocity?

Physics

1 answer:

allsm [11]2 years ago

6 0

Answer:

v = 0.33 [m/s]

Explanation:

We must remember that speed is defined as the relationship between the displacement in a given time. In this way, we can propose the following equation.

$v=d/t$

where:

v = velocity [m/s]

d = displacement = 40 [m]

t = 2 [min] = 120 [s]

Now replacing we have:

$v=40/120\\v=0.33[m/s]$

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A straight section of silver wire has a cross sectional area A=2.0 mm2. A total of 9.4×1018 electrons pass through the wire in 3

Sergio [31]

Answer:

8.08 x 10^-5 m

Explanation:

A = 2 mm^2 = 2 x 10^-6 m^2

Total number of electrons, N = 9.4 x 10^18

time, t = 3 s

n = 5.8 x 10^28 electrons/ m^3

Current, i = Q / t = N x e / t = (9.4 x 10^18 x 1.6 x 10^-19) / 3 = 0.5 A

Let vd be the drift velocity.

i = n e A vd

0.5 = 5.8 x 10^28 x 1.6 x 10^-19 x 2 x 10^-6 x vd

vd = 2.7 x 10^-5 m/s

Distance traveled by the electrons = velocity x time

= vd x t = 2.7 x 10^-5 x 3 = 8.08 x 10^-5 m

3 0

3 years ago

Two objects that are not initially in thermal equilibrium are placed in close contact. After a while, the temperature of the cod

Dima020 [189]

Answer:

If the temperature of the colder object rises by the same amount as the temperature of the hotter object drops, then the specific heats of both objects will be equal.

Explanation:

If the temperature of the colder object rises by the same amount as the temperature of the hotter object drops when the two objects of same mass are brought into contact, then their specific heat capacity is equal.

We can prove this by the equation of heat for the two bodies:

According to given condition,

$\Delta T_1=\Delta T_2$

$\frac{Q_1}{m_1.c_1} = \frac{Q_2}{m_2.c_2}$

when there is no heat loss from the system of two bodies then $Q_1=Q_2$

$\frac{1}{m.c_1} =\frac{1}{m.c_2}$

$\Rightarrow c_1=c_2$

Thermal conductivity is ultimately affects the rate of heat transfer, however the bodies will attain their final temperature based upon their mass and their specific heat capacities.

The temperature of the colder object will rise twice as much as the temperature of the hotter object only in two cases:

when the specific heat of the colder object is half the specific heat of the hotter object while mass is equal for both.

the mass of colder object is half the mass of the hotter object while their specific heat is same.

3 0

3 years ago

A 4.60 gg coin is placed 19.0 cmcm from the center of a turntable. The coin has static and kinetic coefficients of friction with

Komok [63]

Answer:

62.64 RPM.

Explanation:

Given that

m= 4.6 g

r= 19 cm

μs = 0.820

μk = 0.440.

The angular speed of the turntable = ω rad/s

Condition just before the slipping starts

The maximum value of the static friction force =Centripetal force

$\mu_s\ m g=m\ \omega^2\ r\\ \omega^2=\dfrac{\mu_s\ m g}{m r}\\ \omega=\sqrt{\dfrac{\mu_s\ g}{ r}}\\ \omega=\sqrt{\dfrac{0.82\times 10}{ 0.19}}\ rad/s\\\omega= 6.56\ rad/s$

$\omega=\dfrac{2\pi N}{60}\\N=\dfrac{60\times \omega}{2\pi }\\N=\dfrac{60\times 6.56}{2\pi }\ RPM\\N=62.64\ RPM$

Therefore the speed in RPM will be 62.64 RPM.

5 0

2 years ago

What are the four forms that water takes when it returns to earth from the clouds?

Marina CMI [18]

Precipitation from the sky to the earth can come in several forms. Four types are: 1) Rain 2) Snow 3) Sleet (think of a more liquidity slushy snow) 4) Hail (pretty much solid chunks of ice)

6 0

3 years ago

Newton’s second law states that the acceleration of an object is dependent on 1 variable which is the net force

Darya [45]

I think it’s false. The second law states that the acceleration of an object is dependent upon two variables - the net force acting upon the object and then mass of the object.

7 0

2 years ago