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ruslelena [56]
3 years ago
5

A boat takes 4.0 h to travel 36 km down a river, then 5.0 h to return.how fast is the river flowing

Physics
1 answer:
dem82 [27]3 years ago
5 0
<span>Let us refer to boat speed as X and water speed as Y On the way down the stream, the water speed is added to the speed of the boat: speed of the boat (X) + water speed (Y) is 9km/h When the boat is moving upstream, water speed is taken away from the speed of the boat: Speed of the boat (X) - water speed (Y) is 7.2 km/h Therefore: X + Y = 9 : X - Y = 7.2 2X = 16.2 X = 8.1 X + Y = 9 8.1 + Y = 9 Y = 0.9 The river is flowing at 0.9 km/h</span>
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The mass of an object is 60kg on the surface of the earth what will be its weight on the surface of the moon
iris [78.8K]

Answer:

Wm = 97.2 [N]

Explanation:

We must make it clear that mass and weight are two different terms, the mass is always preserved that is to say this will never vary regardless of the location of the object. While weight is defined as the product of mass by gravitational acceleration.

W = m*g

where:

m = mass = 60 [kg]

g = gravity acceleration = 10 [m/s²]

But in order to calculate the weight of the body on the moon, we must know the gravitational acceleration of the moon. Performing a search of this value on the internet, we find that the moon's gravity is.

gm = 1.62 [m/s²]

Wm = 60*1.62

Wm = 97.2 [N]

8 0
3 years ago
A 3-kg wheel with a radius of 35 cm is spinning in the horizontal plane about a vertical axis through its center at 800 rev/s. A
Kruka [31]

Answer:

\omega_f = 585.37 \ rev/s

Explanation:

given,

mass of wheel(M) = 3 Kg

radius(r) = 35 cm

revolution (ω_i)=  800 rev/s

mass (m)= 1.1 Kg

I_{wheel} = Mr²

when mass attached at the edge

I' = Mr² + mr²

using conservation of angular momentum

I \omega_i = I' \omega_f

(Mr^2) \times 800 = ( M r^2 + m r^2) \omega_f

M\times 800 = ( M + m )\omega_f

3\times 800 = (3+1.1)\times \omega_f

2400 = (4.1)\times \omega_f

\omega_f = 585.37 \ rev/s

3 0
3 years ago
The bottom of cooking utensils are often kept black. Give reason​
stepan [7]

Answer:

absorb more heat and get heated quickly

Explanation:

7 0
3 years ago
The midpoint M of a guitar string is pulled a distance d = 1.7 mm from equilibrium and released. Point M is observed to undergo
nlexa [21]

Answer:

ω = 380π rad/s

Explanation:

The formula for the angular frequency is the oscillation frequency f (hertz) multiplied by 2π

ω = 2πf

then

ω = 2π(190)

ω = 380π rad/s

8 0
2 years ago
What converts organic remains into fossil fuels? 1.chemical reaction 2water 3.heat and pressure
kobusy [5.1K]

Answer:

Heat and pressure

Explanation:

4 0
2 years ago
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