Projectiles physics problem - due tomorrow ;_;

In summary, the problem at hand involves a projectile with mass m and velocity V that divides into two equal pieces, each with mass m/2 and velocity theta degrees from the horizontal. The goal is to determine V1 initial and V2 initial in terms of V, theta, and unit vectors i^ and j^. Conservation of momentum and energy are used to solve equations and find solutions.
  • #1
voodoodoodoo
4
0
hey everybody, i would really appreciate a little help with this.

I have a projectile, labeled zero, with mass m and velocity V. it travels in a parabolic motion until it reaches its apex, at which point it divides into two equal pieces, 1 and 2, with mass m/2 and m/2. Each of these pieces splits off with a velocity theta degrees from the horizontal.

Now, i need to determine V1 initial and V2 initial in terms of V, theta, and unit vectors i^ and j^.

Any help at all would really be appreciated - i have AIM(antigravityjesus) and MSN (antigravityjesus@hotmail.com).
Thanks!
 
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  • #2
oh, forgot to say, this is the third part - i already found Delta K / K initial and solved some change-in-K relative to Theta equations.

The problem is, if i sub kinetic energy = kinetic energy into conservation of momentum, i get V = V.

Can i somehow use my Delta K/K equation here? I am at a loss.

Thanks.
 
  • #3
okay, this is what I've done:

1/2 m V^2 = 1/2 m 1/2 v1i ^ 2 + 1/2 m 1/2 v2i ^ 2
which equates to
V^2 = v1i^2 + v2i^2 / 4mV = mv1/2 + mv2/2
which equates to
V = (v1+v2)/2
V^2 = (v1^2 + 2v1v2 + v2^2)/4
... which doesent directly equal v1i^2 + v2i^2 / 4 ... neat. let me see if i just accidentally solved something!

The problem is, i don't have any equations with theta in it.
 
  • #4
nope, just gives me v1=0 and v2=0. darn.
 
  • #5
voodoodoodoo said:
okay, this is what I've done:

1/2 m V^2 = 1/2 m 1/2 v1i ^ 2 + 1/2 m 1/2 v2i ^ 2
which equates to
V^2 = v1i^2 + v2i^2 / 4


mV = mv1/2 + mv2/2
which equates to
V = (v1+v2)/2
V^2 = (v1^2 + 2v1v2 + v2^2)/4
... which doesent directly equal v1i^2 + v2i^2 / 4 ... neat. let me see if i just accidentally solved something!

The problem is, i don't have any equations with theta in it.
Kinetic energy cannot be conserved in this process. It is first a conservation of momentum problem. If the angle θ is given, or your answers are supposed to be expressed in terms of θ then all you need is conservation of momentum.
voodoodoodoo said:
oh, forgot to say, this is the third part - i already found Delta K / K initial and solved some change-in-K relative to Theta equations.

The problem is, if i sub kinetic energy = kinetic energy into conservation of momentum, i get V = V.

Can i somehow use my Delta K/K equation here? I am at a loss.

Thanks.
You can't find the change in kinetic energy without using momentum conservation to find the velocites, so I really don't get what you are saying here.
 

Related to Projectiles physics problem - due tomorrow ;_;

1. What is a projectile?

A projectile is any object that is thrown or launched into the air and is subject to the force of gravity. Examples of projectiles include a baseball being thrown by a pitcher or a cannonball being fired from a cannon.

2. How do you calculate the velocity of a projectile?

The velocity of a projectile can be calculated using the formula v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration due to gravity (9.8 m/s^2), and t is the time elapsed.

3. How does air resistance affect a projectile's motion?

Air resistance, also known as drag, can slow down the motion of a projectile by creating an opposing force. The amount of air resistance depends on the size, shape, and speed of the projectile. In some cases, air resistance may cause a projectile to deviate from its intended path.

4. What is the range of a projectile?

The range of a projectile is the horizontal distance it travels before hitting the ground. It can be calculated using the formula R = v^2 * sin(2θ) / g, where R is the range, v is the initial velocity, θ is the angle of launch, and g is the acceleration due to gravity.

5. How can I solve a projectile physics problem?

To solve a projectile physics problem, you will need to use the equations of motion and apply them to the specific scenario given. It is important to accurately identify the initial and final conditions of the projectile, such as initial height, initial velocity, and angle of launch. Once you have the necessary information, you can use the equations to calculate the unknown quantities.

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