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3 years ago

Before using wind energy to produce electricity, humans used wind energy to produce PLEASE ANSWER QUICKLY

Physics

1 answer:

topjm [15]3 years ago

8 0

Answer:

Water

Explanation:

windmills were used to bring water to farms in ancient times.

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Point P is on the rim of a wheel of radius 2.0 m. At time t = 0, the wheel is at rest, and P is on the x-axis. The wheel undergo

oksian1 [2.3K]

Answer:

e). $a = 0.066 m/s^2$

Explanation:

As we know that wheel is turned by 90 degree angle

so the angular speed of the wheel is given as

$\omega_f^2 - \omega_i^2 = 2\alpha \theta$

now we have

$\omega_f^2 - 0 = 2(0.01)(\frac{\pi}{2})$

$\omega = 0.177 rad/s$

now the centripetal acceleration of the point P is given as

$a_c = \omega^2 R$

$a_c = (0.177)^2(2)$

$a_c = 0.063 m/s^2$

tangential acceleration is given as

$a_t = R\alpha$

$a_t = 2(0.01)$

$a_t = 0.02 m/s^2$

now net acceleration is given as

$a = \sqrt{a_t^2 + a_c^2}$

$a = \sqrt{0.02^2 + 0.063^2}$

$a = 0.066 m/s^2$

8 0

3 years ago

what is the force that opposes the movement of two surfaces that are in contact and are sliding over each other? and it is not f

SCORPION-xisa [38]

Answer:

Friction

Explanation: is the force that opposes motion between any surfaces that are in contact. There are four types of friction: static, sliding, rolling, and fluid friction. Static friction acts on objects when they are resting on a surface.Nov 3, 2021

7 0

2 years ago

Read 2 more answers

Which would be the best example to demonstrate the principle of conservation of energy? A) a stone is crushed B) light bends aro

Daniel [21]

The answer is a pendulum swings back an forth.

6 0

3 years ago

Read 2 more answers

Projectile A is launched horizontally at a speed of 20. Meters per second from the top of a cliff and strikes a level surface be

miv72 [106K]

consider the motion of projectile A in vertical direction :

v₀ = initial velocity of projectile A in vertical direction = 0 m/s (since the projectile was launched horizontally)

a = acceleration of the projectile = g = acceleration due to gravity = 9.8 m/s²

t = time of travel for projectile A = 3.0 seconds

Y = vertical displacement of projectile A = height of the cliff = h = ?

using the kinematics equation along the vertical direction as

Y = v₀ t + (0.5) a t²

h = (0) (3.0) + (0.5) (9.8) (3.0)²

h = 44.1 m

4 0

3 years ago

A 45.0-kg girl is standing on a 168-kg plank. The plank, originally at rest, is free to slide on a frozen lake, which is a flat,

muminat

Answer:

The speed of the plank relative to the ice is:

$v_{p}=-0.33\: m/s$

Explanation:

Here we can use momentum conservation. Do not forget it is relative to the ice.

$m_{g}v_{g}+m_{p}v_{p}=0$ (1)

Where:

m(g) is the mass of the girl
m(p) is the mass of the plank
v(g) is the speed of the girl
v(p) is the speed of the plank

Now, as we have relative velocities, we have:

$v_{g/b}=v_{g}-v_{p}=1.55 \: m/s$ (2)

v(g/b) is the speed of the girl relative to the plank

Solving the system of equations (1) and (2)

$45v_{g}+168v_{p}=0$

$v_{g}-v_{p}=1.55$

$v_{p}=-0.33\: m/s$

I hope it helps you!

8 0

3 years ago