Help Zone

OrZen2798

J'aurais besoin d'aide en physique pour un devoir. (loi d'ohm, la puissance et les differents circuits electriques.)

HibouHabile8386

En laboratoire, dans le but de trouver l’indice de réfraction d’une substance inconnue et ainsi identifier la nature du liquide, nous avons pointé un laser à travers d’une substance inconnue (contenu dans un contenant de forme demi-cercle), à des angles différentes par rapport à la normal afin de mesurer l’angle de réfraction ( θ2 ). Ainsi, grâce a ces angles de réfraction, nous avons déterminer l’indice de refraction moyen (avec la loi de Snell-Descartes) qui nous servirai à d’identifier la substance. Est ce que vous pouvez m’aider à identifier quelques cause d’erreurs dans l’expérience à l’aide de cette délimitation?

FraiseSage527

Bonjour!

J'étudie présentement l'oeil en physique et j'avais une question.

On dit que l'indice de réfraction de l'eau est comparable à celui de la cornée (dans l'oeil), donc logiquement, il n'y aurait pas de déviation de rayons lumineux et l'image serait nette.

Mais pourquoi se fait-il qu'en vrai, nous voyons flou sous l'eau?

Merci

HippopotameTurquoise8599

Bonjour,

J'ai de la difficulté avec un problème en physique

Le voici:

Une mini-fusée de 70 g est lancée à l’aide d’un moteur à poudre noire qui lui donne une poussée de 3 N pendant 0,75 s. Cette poussée lui procure une accélération vers le haut de 33 m s-2 pendant ces 0,75 s. Par la suite, la fusée est en chute libre. Calculez la hauteur maximale atteinte par la mini-fusée.

Je ne sais pas comment débuter la résolution de ce problème.

Merci!

NicePearl6852

Hi! I really really need help with this question, please. I am getting all the answers wrong and I do not know how to solve it.

Ce contenu est protégé par le droit d'auteur. Toute reproduction à l'extérieur des forums Alloprof est interdite et pourra être considérée comme une violation du droit d'auteur.

NicePearl6852

Hello!

I sent a question a few minutes ago and received an answer. However, because I cannot respond back on the same post, I am putting the answer here since I still need a bit of help :)

The spring scale reads the measures in Newtons, so I know I can find the force with that. However, I am not sure how to do the procedure experimentally more specifically. I was thinking I could pull the person in the cart with a constant force for a certain distance and a certain amount of time to find it's constant velocity. Then I could release the person and measure the distance and time taken to stop, so the constant velocity calculated earlier would be my Vinitial and Vfinal=0. Finally, with that data, I could manipulate the equations to find the unknown. Does that sound right?

Also, would the acceleration calculated from the kinematic equations be same one that is used in F=ma and the force with which I pulled the person is F. So the only thing missing would be m, right?

Thanks!!

NicePearl6852

Hello!

I have a lab that involves Newton's law. Basically, one person has to sit on a moving cart and we are required to find the weight of the person and the cart together experimentally. We cannot weight them. However, we have a rope, a spring scale, a timer and tape measure. I am not sure exactly how to proceed. We can use newton's second law (F= ma) to find the acceleration and we can also use the kinematic equations. Can you please help me with the procedure? What steps should I do?

Thank you!

TomateSupra7536

Hello!

I don’t understand anything concerning the focus in the theory of light rays in spherical mirrors. The only thing I understand is that the focus is a point on the main axis, between the center of curvature and the top of the mirror ...

TomateSupra7536

An electronic device consumes 4.1 kW during a week. It dissipates 230 W per day in heat, loses 2000 kW per week due to the light it emits and loses 50 kW per day for another mysterious cause. How much energy is used for the computing functions of the electronic device and what is its percentage of efficiency?

GammaRabbit8261

I have a physics problem. I can't seem to find a way to solve it.

A cart of mass 500 kg is rolling with a speed of 5 m/s on a railway track. There is very little friction between the tracks and the cart. You apply a constant force on the cart in the direction opposite to its velocity. From the moment you start applying the force, the cart moves 30 m before coming to a stop. What was the approximate magnitude of the force you applied?

TomateSupra7536

Why do we sometimes calculate the work with the cosinus of the angle between the force and the displacement and sometimes without it? Is this in a special case or an exception?

TomateSupra7536

The Perseverance robot weighs 1025 kg on Earth. What will be its weight on Mars? Can you help me?

LucidWhale7282

Why do we sometimes calculate the work with the cos of the angle between the force and the displacement and sometimes without? Is this in a special case or an exception?

LucidWhale7282

Hi! In a problem, I am told that the work done on an object is 250 J and that it moves 7.5 m by a force with an orientation of 45 °. How do I know the value of the force from this?

Thank you !

LucidWhale7282

Hi! Why does changing tires help grip? Thanks

LucidWhale7282

Hi! What is a lubricant used for in a mechanism? Can you give me an example? Thank youuu

HumbleArmadillo3023

What is the difference between weight and mass? Thank you for helping me; I do not understand!!

HumbleArmadillo3023

How is the phenomenon of dispersion explained?

HumbleArmadillo3023

Hi!

How come when I have writing on my sweater and I look at myself in the mirror, I see the writing backwards?

Thank you for your time: D

HumbleArmadillo3023

Hi! Could someone explain to me how white light can scatter in full color when it passes through a prism?

HumbleArmadillo3023

Hi! I’m confusing refraction and reflection. When I look at myself in a mirror, which of the two concepts is it? And what about when I see my straw strangely when it's in my glass of water? Thank you for your help!

FairTangerine2097

What is the difference between friction and grip?

HumbleArmadillo3023

How do you distinguish different types of forces (I am in the ATS program)?

HumbleArmadillo3023

Hello, can you explain to me the difference between the resultant and the balancing force ?? Thank you :))

HumbleArmadillo3023

What is the difference between potential energy and kinetic energy?

HumbleArmadillo3023

Why can't we create energy? How do power plants work if they don't create electricity?

HumbleArmadillo3023

I do not understand what work is in physics?

FairTangerine2097

How do we go from m/s to km/h and vice versa? Also, how do you convert velocities using position and time measurements?

FairTangerine2097

Hello! In my assignment, I have to find the displacement in meters of a car if it has driven at 1.5 m / s for 30 seconds. What should I do?

SkillfulGrasshopper3789

Hello !

In physics, what is the difference between a closed system and an isolated system?

Thanks in advance: D

Help Zone

Physics

Physics

Filters

32

Questions

32

Explanations

Help Zone

Physics

Physics

32

Questions

32

Explanations

Discussion List