# Projectile motion (magnitude and direction)

• blazeuofa
In summary, the conversation discusses determining the magnitude and direction of a projectile's velocity 4 seconds after being fired at a speed of 45 m/s and an angle of 40 degrees. The solution involves finding the vertical and horizontal components of the velocity, using kinematics equations, and finding the resultant vector. One person expresses confusion, but the other offers to explain further if needed.
blazeuofa

## Homework Statement

A projectile is fired at a speed of 45 m/s at an angle of 40 degrees above horizontal. Determine the magnitude and direction of its velocity 4 seconds later.

ax=0 ay=-g

## The Attempt at a Solution

find the vy and the vx after 4 seconds and find the resultant vector.

needlottahelp said:
find the vy and the vx after 4 seconds and find the resultant vector.

yeah i don't get how to do that though

oh hahah ok well
Given: vi= 45 m/s and t = 4
so vyi = sin (40) vi and vxi = cos (40) vi

and to find the speed in four seconds you use the kinematics equation
vyf = vyi + (ay) (t) and velocity in the horizontal remains constant since ax = 0

find those to values and vf = sqrt ( vyf^2 + vxf ^2)

Do you understand it? if not I'll try to explain it a bit more

yeah i got it thanks

## What is projectile motion?

Projectile motion is the motion of an object that is thrown or launched into the air and then moves under the force of gravity. It follows a curved path called a parabola.

## What determines the magnitude of projectile motion?

The magnitude of projectile motion is determined by the initial velocity and angle of launch. The greater the initial velocity, the greater the magnitude of the motion. The angle of launch also affects the magnitude, with a higher angle resulting in a greater vertical displacement.

## How is the direction of projectile motion determined?

The direction of projectile motion is determined by the initial angle of launch. The object will always move along the same path as the angle of launch, so a higher angle will result in a greater vertical displacement and a lower angle will result in a smaller vertical displacement.

## What factors affect the magnitude and direction of projectile motion?

The magnitude and direction of projectile motion are affected by factors such as air resistance, wind, and the shape and mass of the object. These factors can alter the trajectory and speed of the projectile, resulting in a different magnitude and direction of motion.

## What is the difference between horizontal and vertical projectile motion?

Horizontal projectile motion is motion along the x-axis, where the initial velocity is entirely horizontal and there is no initial vertical velocity. Vertical projectile motion is motion along the y-axis, where the initial velocity has both horizontal and vertical components. Additionally, the acceleration due to gravity affects vertical motion, but not horizontal motion.

• Introductory Physics Homework Help
Replies
4
Views
1K
• Introductory Physics Homework Help
Replies
11
Views
895
• Introductory Physics Homework Help
Replies
3
Views
3K
• Introductory Physics Homework Help
Replies
18
Views
1K
• Introductory Physics Homework Help
Replies
3
Views
1K
• Introductory Physics Homework Help
Replies
3
Views
1K
• Introductory Physics Homework Help
Replies
15
Views
1K
• Introductory Physics Homework Help
Replies
1
Views
1K
• Introductory Physics Homework Help
Replies
15
Views
21K
• Introductory Physics Homework Help
Replies
2
Views
2K