Help! I Need a Problem Involving Free Fall & Relative Velocity!

In summary, free fall is when an object is only influenced by gravity, while relative velocity is the velocity of an object in relation to a reference point. Some common examples of free fall include objects falling from a height and skydiving, while relative velocity can be seen when a person walks on a moving train or a boat travels downstream in a river. Free fall and relative velocity are related in that the relative velocity takes into account the movement of both the object and the observer, and in free fall, the relative velocity is the sum of the object's velocity and the observer's velocity. The equations for calculating free fall and relative velocity are v = gt and v = u + v<sub>0</sub>, respectively. Air resistance can
  • #1
LastBloomingFlower
15
0
I have to make up or find a problem that invovles free fall velocity AND relative velocity! Can anyone find/make up a problem for that? HELP!
 
Physics news on Phys.org
  • #2
Why not make a problem with two skydivers, where one jumps out of the plane a couple seconds ahead of another. Their velocities will function exponentially until terminal velocity, and you can give the speed of the first skydiver from the pilots perspective assuming his frame is inertial, then ask for the same speed as perceived by the second skydiver.
 
  • #3


One possible problem that involves free fall and relative velocity could be the following:

A ball is thrown off the top of a building with an initial velocity of 20 m/s at an angle of 30 degrees above the horizontal. At the same time, a person on the ground is running towards the building with a velocity of 5 m/s. How far from the base of the building will the ball land and what will be its final velocity when it hits the ground?

To solve this problem, we can use the equations for free fall and relative velocity. The ball's vertical motion can be described by the equation y = y0 + v0y t - 1/2gt^2, where y0 is the initial height (in this case, the height of the building), v0y is the initial vertical velocity (in this case, 10 m/s), t is the time, and g is the acceleration due to gravity (9.8 m/s^2). The ball's horizontal motion can be described by the equation x = x0 + v0x t, where x0 is the initial horizontal position (in this case, 0), v0x is the initial horizontal velocity (in this case, 10√3 m/s), and t is the time.

To find the time at which the ball hits the ground, we can set y = 0 and solve for t. This gives us t = 2 seconds. Plugging this value into the equation for x, we can find that the ball will land 20√3 meters away from the building.

To find the final velocity of the ball when it hits the ground, we can use the equation v = v0 + at, where v0 is the initial velocity (in this case, 20 m/s), a is the acceleration (in this case, -9.8 m/s^2), and t is the time. Plugging in t = 2 seconds, we can find that the final velocity of the ball when it hits the ground will be 0 m/s.

Therefore, the ball will land 20√3 meters away from the building and its final velocity will be 0 m/s. This problem demonstrates the concept of relative velocity as the ball's motion is affected by the person's motion on the ground.
 

What is free fall and relative velocity?

Free fall is the motion of an object under the sole influence of gravity, where the only force acting on the object is the force of gravity. Relative velocity is the velocity of an object in relation to a reference point or observer.

What are some common real-life examples of free fall and relative velocity?

Some common examples of free fall include objects falling from a height, skydiving, and roller coasters. Relative velocity can be seen in situations such as a person walking on a moving train or a boat traveling downstream in a river.

How is free fall and relative velocity related?

In free fall, an object's velocity is constantly changing due to the acceleration of gravity. Relative velocity takes into account the movement of both the object and the observer, so in free fall, the relative velocity would be the sum of the object's velocity and the observer's velocity.

What is the equation for calculating free fall and relative velocity?

The equation for calculating free fall is v = gt, where v is the final velocity, g is the acceleration due to gravity, and t is the time. The equation for relative velocity is v = u + v0, where v is the relative velocity, u is the velocity of the object, and v0 is the velocity of the observer.

How does air resistance affect free fall and relative velocity?

Air resistance, or drag, can affect an object's free fall by slowing down its descent. This means that the acceleration due to gravity is not constant, and the object's velocity will not change at a constant rate. Air resistance also affects relative velocity by changing the velocity of the object in relation to the observer, as the object's movement is influenced by the resistance of the air.

Similar threads

  • Introductory Physics Homework Help
Replies
5
Views
710
  • Introductory Physics Homework Help
Replies
28
Views
2K
  • Introductory Physics Homework Help
Replies
3
Views
229
  • Introductory Physics Homework Help
Replies
1
Views
778
  • Introductory Physics Homework Help
Replies
33
Views
815
  • Introductory Physics Homework Help
Replies
3
Views
247
Replies
20
Views
788
  • Introductory Physics Homework Help
Replies
25
Views
1K
  • Introductory Physics Homework Help
Replies
16
Views
593
  • Introductory Physics Homework Help
Replies
6
Views
1K
Back
Top