motions in phyics

[computerages]

Hello everyone!

 

I have a few questions about motions.

Here they are :-D

• What does it mean when you use the word "magnitude"?
  
• What is the difference between vector and scalar & displacement and distance? Please explain that with examples (if possible) becuse I already know the meanings of them...
  
• How do we work with velocity-time graph?
  
• Please explain these formulas in details: F=ma

Thanks

[LazerFazer]

Hello there,

 

I'll try to answer your questions as best as I can. Here goes:

 

Magnitude simply refers to the 'length' of a vector. magnitude=sqrt(Vx^2+Vy^2) where Vx is the x-component and Vy is the y-component of the vector.

 

A vector is a scalar with direction. For example 10 m/s is a scalar speed. The vector VELOCITY would be something like 10 m/s Due North. Same with displacement, etc.

 

What do you need to know about velocity time graphs? The slope is the acceleration, and the area under the curve is the displacement. One of the more useful graphs, actually.

 

F=ma. Force equals mass times an acceleration. That would be Newton's second law of motion, a body at constant velocity will continue at that velocity until it is acted upon by an outside force. So the body has an acceleration, and thus a force must act on it to cause this acceleration. Since the acceleration is directly proportional to the force exerted on it, the ratio of the force to the acceleration is a constant (for a set body), also known as the mass of the body.

 

Hope this helps. If you have more questions, post them and we'll try to help you.

 

Cheers,

Lazer Fazer

[jordan]

What does it mean when you use the word "magnitude"?

Magnitude just means the amount, or strength, of something. It doesn't include the direction of the motion. Acceleration is typically measured as X m/sec² North (or any other direction). But it can also be said that the same object is accelerating with magnitude X.

 

What is the difference between vector and scalar & displacement and distance? Please explain that with examples (if possible) becuse I already know the meanings of them...

Vector- A measure of magnitude and direction of an object. (Magnitude is coming in again).

Scalar- Just the magnitude, no direction of motion is given.

Displacement- A measure of how far something has traveled with the direction it traveled in.

Distance- A measure of the total motion of an object.

 

Something moving 5m up:

Distance: 5m

Displacement: 5m up

 

Something moving 5m up and then 5m down:

Distance: 10m

Displacement: 0m (the directions and distances cancel each other out)

 

Something moving 3m north and 4m east:

Distance: 7m

Displacement: 5m northeast

 

How do we work with velocity-time graph?

This is a really broad question. Is there a particular thing you don't understand?

 

Please explain these formulas in details: F=ma

Thanks

Also very general. It has applications is basic physics everywhere. There's nothing really to explain other than that is reads Force equals mass times acceleration. As you start doing problems you'll use it a bunch.

[computerages]

Hello everybody!

 

Thanks for the help, first of all.

 

Now, I am actually beginning to understand the basic concepts of physics. I have a few more questions to ask...

 

What do you mean when you use the term "proportional"?

 

What is the purpose of mass in the "F=MA" function?? If the rate of acceleration due to gravity will be same for two objects having different mass, so why does the mass involve in the force which is being applied to cause acceleration?

 

How does d=Vi(t)+1/2(a)(t)^2 function work and helps us to find out the actual distance.

 

Thanks for the help again, guys...!!

 

I shall post more questions if I find something incomprehensible.

[computerages]

Hi there,

 

I have three more questions regarding motions from my homework...

 

1. Assume an airplane starts with an initial speed of zero and accelerates at 20 meters per second^2. State the distance traveled, the speed, and the acceleration for the first five seconds.

 

First Sec. D=10m s=10m/s a=20m/s^2

 

Second Sec. D=40m s=20m/s a=20m/s^2

 

Third Sec. D=90m s=45m/s a=20m/s^2

 

Fourth Sec. D=160m s=80m/s a=20m/s^2

 

Fifth Sec. D=250m s=125m/s a=20m/s^2

 

I don't know whether my answers are valid or not. If they are valid, I still don't get anything out of them as I just used the formulas to solve the problem.

 

2. A projectile is shot straight up with an initial speed of 98.1 m/s. How long does the projectile remains in the air? How high does it rise?

 

I don't understand the entire concept of this question. How is it possible to find the max. height and other asked variables if the speed is only given.

 

3. A steel projectile is shot horizontally at a speed of 20 m/s from the top of a tower that is 49 meters high. How far from the base of the tower does it hit the ground?

 

This is the hardest question I've ever encountered in my life. Please explain.

 

Thanks everybody for the help.!! It is greatly appreciated.

[swansont]

Hi there' date='

 

I have three more questions regarding motions from my homework...

 

[b']1. Assume an airplane starts with an initial speed of zero and accelerates at 20 meters per second^2. State the distance traveled, the speed, and the acceleration for the first five seconds.[/b]

 

First Sec. D=10m s=10m/s a=20m/s^2

 

Second Sec. D=40m s=20m/s a=20m/s^2

 

Third Sec. D=90m s=45m/s a=20m/s^2

 

Fourth Sec. D=160m s=80m/s a=20m/s^2

 

Fifth Sec. D=250m s=125m/s a=20m/s^2

 

I don't know whether my answers are valid or not. If they are valid, I still don't get anything out of them as I just used the formulas to solve the problem.

 

2. A projectile is shot straight up with an initial speed of 98.1 m/s. How long does the projectile remains in the air? How high does it rise?

 

I don't understand the entire concept of this question. How is it possible to find the max. height and other asked variables if the speed is only given.

 

3. A steel projectile is shot horizontally at a speed of 20 m/s from the top of a tower that is 49 meters high. How far from the base of the tower does it hit the ground?

 

This is the hardest question I've ever encountered in my life. Please explain.

 

Thanks everybody for the help.!! It is greatly appreciated.

 

1. v = at s = v₀t + 1/2 at²

 

so v = 20*5 = 100 m/s you can find s with the other equation

 

2. usng the equation for s above, a= -9.8 m/s². What is the displacement after it hits the ground? At what point will it be at its maximum height? After answering those questions, you can use that information in the formula.

 

3. The horizontal motion and vertical motion are separate. If you can find how long it takes to fall that distance, you can then use the horizontal speed to see how far it went.