Projectile Motion velocity vector Problem

In summary, the projectile's velocity after 2.0 s is 50 m/s with an angle of 53.13 degrees. The difference between speed and velocity is that velocity includes direction. The acceleration of the projectile is -10 m/s^2, not +10 m/s^2 as mistakenly used in the calculation. The correct formula to use is v_y = v_y(0) + a t.
  • #1
Lori
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I want to know if i did this problem correctly!

Problem: A projectile is traveling with velocity vector v = (30.00 m/s)i + (20.0 m/s)j when it experiences an acceleration of vector a = (-10.00 m/s^2)j. What is its velocity after 2.0 s? What is its speed after 2.0 s?


My work:

Vy = V0y - gt = 20 - (-10)2 = 40 m/s
Vx = 30 (constant)

Vector v = sqrt( vy^2 +vx^2) = 50
Angle = atan(vy/vx) = 53.13 degrees

Answer:

Speed is 50 m/s
Velcoity is 50 m/s with angle 53.13 degrees


What's the difference between speed and velocity? They are the same except the velocity has direction right?
 
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  • #3
Lori said:
Problem: A projectile is traveling with velocity vector v = (30.00 m/s)i + (20.0 m/s)j when it experiences an acceleration of vector a = (-10.00 m/s^2)j. What is its velocity after 2.0 s? What is its speed after 2.0 s?

My work:
Vy = V0y - gt = 20 - (-10)2 = 40 m/s
why the 2 minus signs for g?

The problem says a = (-10 m/s)j, but you used g = (+10 m/s) j for the acceleration of gravity.
I think a is supposed to be the acceleration of gravity, and you can just use [itex] v_y = v_y(0) + a t [/itex]
 
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FAQ: Projectile Motion velocity vector Problem

1. What is projectile motion velocity vector problem?

Projectile motion velocity vector problem is a physics problem that involves determining the velocity of an object that is launched into the air at an angle. The object follows a curved path, known as a projectile trajectory, due to the force of gravity acting on it.

2. How is the velocity vector of a projectile calculated?

The velocity vector of a projectile is calculated by breaking it down into its horizontal and vertical components. The horizontal component remains constant throughout the projectile's motion, while the vertical component changes due to the acceleration of gravity. The two components are then combined to form the velocity vector.

3. What factors affect the velocity vector of a projectile?

The velocity vector of a projectile is affected by the initial velocity, angle of launch, mass of the object, and the force of gravity. Air resistance can also play a role in altering the velocity vector, but it is often neglected in simple projectile motion problems.

4. How does the velocity vector change during the course of projectile motion?

The velocity vector of a projectile changes due to the acceleration of gravity. As the object moves upward, the vertical component of the velocity decreases until it reaches its maximum height, where it becomes zero. As the object falls back to the ground, the vertical component increases, while the horizontal component remains constant.

5. What is the importance of understanding projectile motion velocity vector problem?

Understanding projectile motion velocity vector problem is important in various fields, such as engineering, sports, and military, where the motion of objects in the air needs to be predicted and controlled. It also helps in understanding the fundamental principles of motion and gravity in physics.

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