Can someone please help?

Betty is sitting on of her surfboard out in the ocean. She is waiting for the perfect wave to come along so she can ride it in t

givi [52]

Crest is the part of the wave which does this.

A sound wave is the sample of disturbance resulting from the movement of strength visiting through a medium, including air, water or every other liquid or stable remember as it propagates far from the supply of the sound.

The sound waves are generated by a sound source, such as the vibrating diaphragm of a stereo speaker. The sound source creates vibrations in the surrounding medium. because the supply continues to vibrate the medium, the vibrations propagate far from the supply at the rate of sound, hence forming the sound wave.

A sound wave is not a transverse wave with crests and troughs, however alternatively a longitudinal wave with compressions and rarefactions.

Learn more about wave here:- brainly.com/question/1199084

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7 0

10 months ago

If she can throw each rock with a speed of 7.5 m/s relative to the ground, causing the wagon to move, how many rocks must she th

Stels [109]

Complete question:

A child sits in a wagon with a pile of 0.64-kg rocks. If she can throw each rock with a speed of 7.5 m/s relative to the ground, causing the wagon to move, how many rocks must she throw per minute to maintain a constant average speed against a 3.9-N force of friction

Answer:

The number of rocks per minutes thrown is 49 rocks/min

Explanation:

Given;

mass of the rock, m = 0.64 kg

speed of the rock, v = 7.5 m/s

frictional force, $f_k$ = 3.9 N

For an object to move at a constant speed, the applied force must be equal to the frictional force.

$f_k = N(F_a)\\\\f_k = N(\frac{mv}{t})\\\\f_k = \frac{N}{t} (mv)\\\\\frac{N}{t} = \frac{f_k}{mv}$

where;

$F_a$ is the applied force

N/t is the number of rocks per minutes thrown

Substitute the given parameters;

$\frac{N}{t} = \frac{f_k}{mv}\\\\ \frac{N}{t} = \frac{3.9}{0.64*7.5}\\\\ \frac{N}{t} = 0.8125 \ \frac{rocks}{second} * \frac{60 \ seconds}{1 \ min} = 48.75 \ \frac{rocks}{min} \$

Approximately 49 rocks/min

5 0

3 years ago

||||| A 1.5 kg block and a 2.5 kg block are attached to opposite ends of a light rope. The rope hangs over a solid, frictionless

amid [387]

Answer

The lighter block will have the Positive Acceleration that is +2.45 m/s square.

A (1.5 Kg) = + 2.45 m/s square

Explanation:

To solve this there is a hard way to do this and there is an easy way to do this. The hard way is to solve Newton's second law for each block individually and then combine them and you get two equations with two unknowns. you try your best to solve the algebra without losing any sins but lets be honest it usually goes wrong.

So the easy way to do this the way to get the magnitude of the acceleration of the blocks. That is to say that i want to know the magnitude at which 2.5 Kg block accelerates or 1.5 Kg block accelerates when the the blocks were released.

Take the net external force that tries to make system go and divide it by total mass of the the system.

A (of System) = F(net external force) / m (total mass of system)

This is the quick way to know the magnitude of acceleration of the objects in the system. But this is only possible if the system is moved in same magnitude of acceleration that is 2.5 Kg block will move downward and 1.5 Kg block will move upward with the same magnitude. So here in this case we have friction-less pulley and the blocks will move with the same magnitude of acceleration.

To find the external forces

External forces are the forces which exerted on the objects in our system from the objects outside of our system. So one external force is the force of gravity. Both 2.5 Kg block and the force of gravity will be in downward direction.

Force of gravity on 2.5 Kg block

F = + (2.5 x 9.8) = 24.5

After releasing the rope the 2.5 Kg block will drive the system and accelerates in downward direction so It will be a positive force.

Force of gravity on 1.5 Kg block

F = - (1.5 x 9.8) = 14.7

The force of gravity on 1.5 Kg block will be negative because it will accelerate in upward or opposite direction of the force of gravity. Because the whole system is moving in one direction but the force of gravity on 1.5 Kg block is opposing the acceleration of the system.

Now divide the the Net external forces by total mass of the blocks that is

A (of System) = F(net external force) / m (total mass of system)

A = (+ 24.5 - 14.7) / 2.5 + 1.5

A = 9.8 / 4

A = 2.45 meter per second square

So the Acceleration of 2.5 Kg block will be Negative that is -2.45 m/s square. Since block is accelerating down and we usually treat down as negative.

A (1.5 Kg) = - 2.45 m/s square

So the Acceleration of 1.5 Kg block will be Positive that is +2.45 m/s square. Since block is accelerating up and we usually treat up as positive.

A (1.5 Kg) = + 2.45 m/s square

4 0

3 years ago

Each of the planets also spins about an axis running through it. True or False

Mnenie [13.5K]

Answer:

True

Explanation:

All the planets have formed from a mass of spinning particles. As they formed from spinning mass the planets are still spinning due to the conservation of angular momentum. Hence all planets spins about an axis running through it.

All planets spin in counterclockwise direction when viewed from above. Except Venus rotates in anticlockwise direction and Uranus' axis of rotation is titled towards its side.

5 0

3 years ago

A potter’s wheel moves from rest to an angular speed of 0.40 rev/s in 37.5 s.

svlad2 [7]

The angular acceleration of the potter's wheel is 0.067 rad/s².

The given parameters:

Final angular speed, ωf = 0.4 rev/s
Time of motion, t = 37.5 s

<h3>What is angular acceleration?</h3>

Angular acceleration of an object is the rate of change of angular speed of the object.

The angular acceleration of the potter's wheel is calculated as follows;

$\alpha = \frac{\Delta \omega }{t} \\\\\alpha = (0.4\ rev/s \times \frac{2 \pi \ rad}{1 \ rev} ) \times \frac{1}{37.5 \ s} \\\\\alpha = 0.067 \ rad/s^2$

Thus, the angular acceleration of the potter's wheel is 0.067 rad/s².

Learn more about angular acceleration here: brainly.com/question/25129606

5 0

2 years ago