Need help with simple position and velocity problems

In summary, the problem involves a particle with a mass of 1 slug moving in a constant force of F= 3i + 10j - 5k lb. The particle starts from rest at position (3,5,-4) and we need to find its position and velocity at t=8 sec. We also need to find the position when the particle is moving at a speed of 20 ft/sec. The second problem involves finding the position and time for a particle moving at a constant force, with given values for velocity and acceleration in both the X and Y directions. The equation for x and y can be found using the given values, and the time can be determined by finding the relationship between x and y on the
  • #1
Pepsi24chevy
65
0
One problem reads: A particle of mass 1 slug is moving in a constant force given as F= 3i + 10j - 5k lb
THe particle starts from rest at position (3,5,-4). What is the poisiton and velocity of the particle at time t= 8 sec.? WHat is the poistion wehn the particle is moving at a speed of 20 ft/sec?

I guess i am confused on how to find the position vector of teh particle at t= 8 sec. I know once i find that i need to subtract it from the orginal position. I then assuem i am going to do an integral? to get the position when the particle is moving at a speed of 20 ft/sec?


HEre is the second problem. I have no idea what to do. I am sure i need to take the derivative of the equation but i dont' know how to apply it.
http://www.mustangmods.com/data/16002/review1.jpg
 
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  • #2
for the second one (taking up and to the right to be positive)
Y Direction
v1 = 20 sin 60
v2 = ?
a = -9.8 m/s^2(gravity points downward
y = ?
X Direction
v1 = 20 cos 60
v2 = 20 cos 60 (No forces in the X direction)
a=0
x=?

and time = ?
Write down an equation for x in terms of what you are given for x. Do the same for y. Now how are x and y related, according to the diagram? Thus find the time, and you can find x, thus y and the point on the parabola.
 
  • #3
I'll be more than happy to help you, but first I need to know what "moving in a constant force" means? I'm almost 100% sure that the problem has the force vector as the net force, meaning that the particle is accelearting. If this is the case, let me know and Ill help you get started. (BTW, yeah, there is a small deal of calc, but not to worry)
 
  • #4
DaMastaofFisix said:
I'll be more than happy to help you, but first I need to know what "moving in a constant force" means? I'm almost 100% sure that the problem has the force vector as the net force, meaning that the particle is accelearting. If this is the case, let me know and Ill help you get started. (BTW, yeah, there is a small deal of calc, but not to worry)
yes, the particle is accelerating.
 

What are position and velocity problems?

Position and velocity problems are mathematical problems that involve calculating the position and/or velocity of an object at a given time, based on its initial conditions and any relevant equations or formulas.

What are some common types of position and velocity problems?

Some common types of position and velocity problems include projectile motion, circular motion, and simple harmonic motion. These problems can involve objects moving in one, two, or three dimensions, and may require the use of kinematic equations or other formulas.

How do I solve a position and velocity problem?

To solve a position and velocity problem, you will need to identify the initial conditions of the object (such as its initial position and velocity), any relevant equations or formulas, and the time at which you want to calculate the position or velocity. You will then plug these values into the appropriate equations and solve for the unknown variable.

What units are used for position and velocity?

In most cases, position is measured in meters (m) and velocity is measured in meters per second (m/s). However, depending on the specific problem, other units such as feet (ft) or kilometers per hour (km/h) may be used.

What are some common mistakes when solving position and velocity problems?

Some common mistakes when solving position and velocity problems include using the wrong units, forgetting to take into account acceleration or other forces acting on the object, and making calculation errors. It is important to carefully read and understand the problem and double check your calculations to avoid these mistakes.

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