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3 years ago

Britain and France signed an entente and became the

Physics

2 answers:

V125BC [204]3 years ago

6 0

<span> Allied Forces. they became the allies.</span>

Shkiper50 [21]3 years ago

5 0

I think B. Allied forces

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A soccer ball of mass 0.4 kg is moving horizontally with a speed of 20 m/s when it is kicked by a player. The kicking force is s

amid [387]

Answer:

v_{f} = 74 m/s, F = 230 N

Explanation:

We can work on this exercise using the relationship between momentum and moment

I = ∫ F dt = Δp

bold indicates vectors

we can write this equations in its components

X axis

Fₓ t = m ( -v_{xo})

Y axis

t = m (v_{yf} - v_{yo})

in this case with the ball it travels horizontally v_{yo} = 0

Let's use trigonometry to write the final velocities and the force

sin 30 = v_{yf} / vf

cos 30 = v_{xf} / vf

v_{yf} = vf sin 30

v_{xf} = vf cos 30

sin40 = F_{y} / F

F_{y} = F sin 40

cos 40 = Fₓ / F

Fₓ = F cos 40

let's substitute

F cos 40 t = m ( cos 30 - vₓ₀)

F sin 40 t = m (v_{f} sin 30-0)

we have two equations and two unknowns, so the system can be solved

F cos 40 0.1 = 0.4 (v_{f} cos 30 - 20)

F sin 40 0.1 = 0.4 v_{f} sin 30

we clear fen the second equation and subtitles in the first

F = 4 sin30 /sin40 v_{f}

F = 3.111 v_{f}

(3,111 v_{f}) cos 40 = 4 v_{f} cos 30 - 80

v_{f} (3,111 cos 40 -4 cos30) = - 80

v_{f} (- 1.0812) = - 80

v_{f} = 73.99

v_{f} = 74 m/s

now we can calculate the force

F = 3.111 73.99

F = 230 N

6 0

3 years ago

You do 120 j of work while pulling your sister back on a swing, whose chain is 5.10 m long. you start with the swing hanging ver

Goryan [66]

The work done to pull the sister back on the swing is equal to the increase in potential energy of the sister:
$W= \Delta U = mg \Delta h$ (1)

where m is the sister's mass, g is the gravitational acceleration and $\Delta h$ is the increase in altitude of the sister with respect to its initial position.

By calling $\theta$ the angle of the chain with respect to the vertical, the increase in altitude is given by
$\Delta h = L - L \cos \theta = L(1 - \cos \theta)$ (2)
where L is the length of the chain.

Putting (2) inside (1), we find
$W= m g L (1 - \cos \theta)$
from which we can find the mass of the sister:
$m = \frac{W}{g L (1 - \cos \theta)} = \frac{120 J}{(9.81 m/s^2)(5.10 m)(1- \cos 32.0^{\circ})} =15.8 kg$

5 0

3 years ago

Two boats start together and race across a 48-km-wide lake and back. Boat A goes across at 48 km/h and returns at 48 km/h. Boat

nika2105 [10]

Answer:

Part 1)

Boat A will win the race

Part 2)

Boat A will win the race by 48 km as the 2nd boat will reach the other end while boat A will just touches the finish line

Part 3)

average velocity must be zero

Explanation: