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Arada [10]
3 years ago
8

A boat heads north in still water at 4.5 m/s directly across a river that is running east at 3.0 m/s. What is the velocity of th

e boat with respect to Earth?
Physics
2 answers:
Fynjy0 [20]3 years ago
4 0
<h2>Velocity of the boat with respect to Earth is 5 m/s 56.31° north of east</h2>

Explanation:

A boat heads north in still water at 4.5 m/s directly across a river that is running east at 3.0 m/s.

Let north be positive y axis and east be positive x axis.

We have

         Velocity of boat = 4.5 j m/s

          Velocity of river = 3 i m/s

Velocity of the boat with respect to Earth = 3 i + 4.5 j

\texttt{Magnitude of velocity = }\sqrt{3^2+4.5^2}\\\\\texttt{Magnitude of velocity = }5.41m/s

\texttt{Angle = }tan^{-1}\left ( \frac{4.5}{3}\right )\\\\\texttt{Angle = }56.31^0

That is 56.31° north of east.

Velocity of the boat with respect to Earth is 5 m/s 56.31° north of east

Ilya [14]3 years ago
3 0

Answer:

5.41 m/s

Explanation:

velocity of boat with respect to water , Vb,w = 4.5 j

velocity of water with respect to ground, Vw,g = 3 i

velocity of boat with respect to water = velocity of boat - velocity of water

Vb,w = Vb, g - Vw, g

4.5 i = Vb,g - 3i

Vb,g = 3 i + 4.5 j

The magnitude of velocity = \sqrt{3^{2}+4.5^{2}} = 5.41 m/s

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A fairgrounds ride spins its occupants inside a flying saucer-shaped container. If the horizontal circular path the riders follo
cestrela7 [59]

Answer:

13.37 rev/min

Explanation:

acceleration due to gravity (g) = 9.8 m/s², centripetal acceleration (a_c) = 1.8 * g = 1.8 * 9.8 m/s² = 17.64 m/s².

r = 9 m

Centripetal acceleration (a_c) is given by:

a_c=\frac{v^2}{r} \\\\v=\sqrt{a_c*r} \\\\v=\sqrt{17.64\ m/s^2*9\ m}\\\\v=12.6\ m/s

The velocity (v) is given by:

v = ωr;  where ω is the angular velocity

Hence:

ω = v/r = 12.6 / 9

ω = 1.4 rad/s

ω = 2πN

N = ω/2π = 1.4 / 2π

N = 0.2228 rev/s

N = 13.37 rev/min

4 0
2 years ago
Why does the density of a substance remain the same for different amount of the substance
tresset_1 [31]

Think of it this way: 
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because that amount doesn't change the (number) PER UNIT.

-- If oranges cost $1 PER POUND, it doesn't matter how many pounds
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-- If a certain salad dressing has 40 calories PER Tablespoon, it doesn't
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-- Density means '(mass) PER unit of volume'.  Whether you have a tiny
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6 0
3 years ago
Help me please i dont understand
Mamont248 [21]

Answer:

0.58

Explanation:

Sinẞ = opposite ÷ hypotenuse

Sinẞ = 5 ÷ 8.6

Sinẞ = 0.5814

Sinẞ ≈ 0.58

5 0
3 years ago
Read 2 more answers
A swift blow with the hand can break a pine board. As the hand hits the board, the kinetic energy of the hand is transformed int
Stells [14]

Answer:

A. The hand must move with a velocity of 6.98 m/s to break the board.

B. Average force on the hand = 1025 N

Explanation:

A.To determine the speed the hand must move with to break the board, the force workdone in breaking the board is found first.

Workdone = force × distance

Minimum force required = 870 N;

Distance moved by board/Deflection in order to break = 1.4 cm = 0.014 M

Workd done = 870 N × 0.014 m = 12.18 Nm or 12.18 J

This work done = Kinetic energy of the hand

Kinetic energy = mv²/2 ; where m is mass and v is velocity

Mass of hand = 0.50 Kg, velocity = ?, K.E. = 12.18 J

v² = 2 KE/m

v = √2KE/m

v = √(2 × 12.18/0.50)

v = 6.98 m/s

Therefore, the hand must move with a velocity of 6.98 m/s to break the board.

B. Average force on the hand

This can be determined using the equation of motion, v² = u² + 2as to find acceleration, since force = mass × acceleration

From the equation of motion, a = v² - u²/2s

At rest, v = 0, u = 6.98, s = 1.2 cm = 0.012 m

a = 0² - 6.98²/ 2 × 0.012

a = -2030 m/s²

Force = 2030 m/s² × 0. 50 kg = 1015 N

Therefore, Average force on the hand = 1025 N

3 0
2 years ago
A pulley system has an efficiency of 74.2%. If you perform 200 J of work, how
Fudgin [204]

Answer:

C

Explanation:

If a pulley system has an efficiency of 74.2%, then only that fraction of the work performed will be useful. 74.2%=0.742. 0.742*200 is about 148J. Hope this helps!

8 0
2 years ago
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