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lorasvet [3.4K]
2 years ago
8

Three swimmers who all swim at the same speed discuss how to cross a river in the shortest amount of time. Swimmer A will swim s

traight across the river at a right angle to the current. Swimmer B reasons that the current will carry A downstream, meaning that A will cover a greater distance to get across and therefore will take a longer time interval. B says he will aim at an upstream angle such that, allowing for the current, he will reach the other side directly across from where he starts, thus covering the shortest distance and arriving first. Swimmer C, reasoning that the time interval needed for B to cross will be longer than B expects because some of B’s effort will be spent battling the current, plans to aim at a downstream angle, so that the current assists rather than opposes him. This way he will be traveling at the highest speed and get across first. Which swimmer gets across first?
Physics
1 answer:
AleksAgata [21]2 years ago
5 0

Answer:

Swimmer A

Explanation:

The time required for a swimmer to cross a river is equal to the width of the river which is divided by the magnitude of the component of the velocity which is parallel to the width of the river.

In the given context, all the three swimmers A, B and C swims in a different angle relative to the direction of the flow of river. The swimmer A swims straight at a direction perpendicular to the direction of current of the river across the width of the river, so A will have the largest velocity component which is parallel to the width of the river. So the time taken by swimmer A will be the least to cross the river.

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During an adiabatic process an object does 100 J of work and its temperature decreases by 5 K. During another process it does 25
Liono4ka [1.6K]

Answer:

The heat capacity for the second process is 15 J/K.

Explanation:

Given that,

Work = 100 J

Change temperature = 5 k

For adiabatic process,

The heat energy always same.

dQ=0

dU=-dW

We need to calculate the number of moles and specific heat

Using formula of heat

dU=nC_{v}dT

nC_{v}=\dfrac{dU}{dT}

Put the value into the formula

nC_{v}=\dfrac{-100}{5}

nC_{v}=-20\ J/K

We need to calculate the heat

Using formula of heat

dQ=nC_{v}(dT_{1})+dW_{1}

Put the value into the formula

dQ=-20\times5+25

dQ=-75\ J

We need to calculate the heat capacity for the second process

Using formula of heat

dQ=nC_{v}(dT_{1})

Put the value into the formula

-75=nC_{v}\times(-5)

nC_{v}=\dfrac{-75}{-5}

nC_{v}=15\ J/K

Hence, The heat capacity for the second process is 15 J/K.

5 0
3 years ago
How many birds have tested positive for West Nile virus?
snow_lady [41]
I believe the last time the dead bird count was updated (12/16/16), there is a count of 1,350 dead birds. There is 1,350 dead birds from 33 countries have tested positive for WNV in 2016.
5 0
3 years ago
A proton moves at a constant velocity of 50m/s along the x axis ,through crossed electric and magnetic fields .The magnetic fiel
shusha [124]

Answer:

42 I THE CORRECT ANSWER

Explanation:

BECAUSE I KNOW

6 0
3 years ago
An ice skater accelerates backward for 5.0 second to final speed of 12m/s. If the acceleration backward was at a a rate of 1.5m/
Lisa [10]

Answer:

Initial velocity, U = 4.5m/s

Explanation:

Given the following data;

Final velocity, v = 12m/s

Time, t = 5 seconds

Acceleration, a = 1.5m/s²

To find the initial velocity, we would use the first equation of motion.

V = U + at

Where;

V is the final velocity.

U is the initial velocity.

a is the acceleration.

t is the time measured in seconds.

Substituting into the equation, we have;

12 = U + 1.5*5

12 = U + 7.5

U = 12 - 7.5

Initial velocity, U = 4.5m/s

3 0
2 years ago
We want to find how much charge is on the electrons in a nickel coin. Follow this method. A nickel coin has a mass of about 4.2
monitta

Answer:

The number of atoms is N = 4.37*10^{22} \ atoms

Explanation:

From the question we are told that

                 The mass of coin  is m_n = 4.2g

                   Number of atom in one mole = n =6.02*10^{23} \ atoms

                   Molar mass of nickel M = 57.8g

Now the relation to obtain the number of atom in  the  nickel coin is

                        N = \frac{Mass \ of Nickel\ coin}{Molar \ mass\ of nickel }  * No\ of\atoms \ in \ \ one\  mole\ of\ nickel

                           = \frac{4.2}{57.8}* 6.02*10^{23}

                           =4.37 *10^{22} atoms

                 

     

8 0
3 years ago
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