Finding Magnitude of Velocity with Variables

In summary: It would stay at or near the Earth's surface.The projectile would be graphed on the right side of a vertex of a parabola if t=VSinA/g. This is why t=VSinA/g.
  • #1
RedRumRiots
1
0

Homework Statement


Romeo tosses a pebble at Juliet's window. Before crashing through the window the pebble is moving horizontally, having traveled a horizontal distance x and a vertical distance y. Find the magnitude and direction of the pebble's velocity as it leaves Romeo's hand.


Homework Equations


I know that Vx=VCosA and Vy=SinA.
Also, t=VSinA/g


The Attempt at a Solution


The attempts are pretty much any relevant equations I can find. There's no real math, except I know that the initial Vy is 0. I also figured if the projectile was graphed it would be the right side of the vertex of the parabola. This is why t=VSinA/g. I do not know where to go from here though. I was thinking of using y=VsinA*t-.5g(t)^2. but I really don't know
 
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  • #2
You know this -

time to hit window, t = x/Vx where Vx is the x velocity

Vy = gt, because Vy=0 at time t ( the sign may be wrong here, Vy is in the opposite direction to g)

y = 1/2 gt^2, distance traveled vertically in time t.

Some manipulation should give what you're looking for.
 
Last edited:
  • #3
I don't understand this. How can we figure out what t is. I do understand that y = .5gt^2. Just not the rest of it. Any help here would be appreciated!
 
  • #4
Hi RedRumriots,

RedRumRiots said:

Homework Statement


Romeo tosses a pebble at Juliet's window. Before crashing through the window the pebble is moving horizontally, having traveled a horizontal distance x and a vertical distance y. Find the magnitude and direction of the pebble's velocity as it leaves Romeo's hand.


Homework Equations


I know that Vx=VCosA and Vy=SinA.
Also, t=VSinA/g


The Attempt at a Solution


The attempts are pretty much any relevant equations I can find. There's no real math, except I know that the initial Vy is 0.

Why do you think the Vy=0 initially? You do know that Vy is zero right before the stone hits the window; what does that tell you about that point of the trajectory?

If Vy=0 initially, then this stone would never move upwards.
 

FAQ: Finding Magnitude of Velocity with Variables

1. What is the formula for finding magnitude of velocity with variables?

The formula for finding magnitude of velocity with variables is velocity = distance/time. This formula is also known as the average velocity formula and is used to calculate the speed or rate at which an object is moving.

2. How do you calculate the distance traveled in a given time period?

To calculate the distance traveled, you can use the formula distance = velocity x time. This formula takes into account the speed (velocity) of the object and the time period in which it is moving to determine the total distance traveled.

3. Can the magnitude of velocity be negative?

Yes, the magnitude of velocity can be negative. This indicates that the object is moving in the opposite direction of the positive axis. For example, if an object is moving west, it will have a negative velocity when compared to a reference point moving east.

4. How does acceleration affect the magnitude of velocity?

Acceleration is the rate at which an object's velocity changes over time. If an object is accelerating, its velocity will increase or decrease, thus affecting the magnitude of its velocity. A positive acceleration will result in an increase in velocity, while a negative acceleration will result in a decrease in velocity.

5. What units are used to measure velocity?

The units used to measure velocity are distance over time, such as meters per second (m/s) or kilometers per hour (km/h). These units represent the amount of distance traveled in a given amount of time and can be converted to different units depending on the needs of the problem.

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