Derive from projectile motion equation

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Homework Help Overview

The discussion revolves around deriving the range of a projectile motion equation, specifically R = v^2 sin(2θ) / g and showing that R = V0^2 / g. The context is introductory physics, focusing on kinematics and projectile motion.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss starting with sketches and velocity-time graphs to understand the motion. There are questions about the feasibility of solving the problem without provided graphs and concerns about lacking knowledge in trigonometry and foundational physics concepts.

Discussion Status

The discussion is ongoing, with some participants suggesting methods to approach the problem, such as using kinematic equations and creating graphs. However, there is a recognition of the need for foundational skills in trigonometry and graphing, which some participants indicate they currently lack.

Contextual Notes

Participants note the absence of a provided graph and express uncertainty about their mathematical skills, particularly in trigonometry, which is essential for the derivation. There is an acknowledgment that this problem may be challenging for someone new to physics.

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Homework Statement



Derive:
R=v^2sin2theta/g

Show that R=V0^2/g

Homework Equations





The Attempt at a Solution



This is my first time to take up physics so I have no idea at all on how to do this, to be honest.
 
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Start with a sketch of the motion, then draw the velocity-time graphs for the horizontal and vertical components.
The area under the horizontal graph is the range R.

This would be a very unusual problem for a first-time physics student.
Normally you would learn things like the definitions for velocity and displacement and drawing graphs and Newton's laws before you get to ballistics.
 
Thank you. There was no graph provided for this. Can this still be solved?
 
Also, I have no sufficient knowledge of trigonometry to be able to derive equations like this.
 
You have to make the graph yourself - it can also be done from the kinematic equations.
You do need trigonometry to divide the initial velocity into horizontal and vertical components.
You also need to know how to find the slope of a line and how to find the areas of a triangle and a rectangle.
If you do not have these skills, or the ability to sketch v-t graphs, then you need to acquire these skills before attempting problems like this one.

There are plenty of online sites that can help you.
 

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