# Projectile motion

[SOLVED] Projectile motion

1. Homework Statement
How do you calculate the projectile motion of an object in the following question?

John is a long jumper. He runs down a track, and jumps as far as he can horizonally. Her take-off velocity is 6.4 m s-1 at 20 degrees from the horizontal.

a) show that the horizontal component of her initial velocity is 6.0m s-1

b) Show that the vertical component of her initial velocity is 2.2 m s-1

c) Explain why the horizontal component of her velocity is constant.

3. The Attempt at a Solution

I know that for a) you use vectors to solve it but I don't know what to do after that and for the others I have no idea what to do so any help is appreciated
1. Homework Statement

2. Homework Equations

3. The Attempt at a Solution

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tiny-tim
Homework Helper
… right-angled triangle …

Hi Paulo!

For a) and b), draw a right-angled triangle.

Can you now see what combination of horizontal and vertical speeds makes 6.4 m s-1 at 20 degrees from the horizontal?

Initial velocity: 6.4 m/s

a)Horizontal component= 6.4 * cosine20 degrees.
>>6 m/s.
b)Vertical component= 6.4 * sine 20 degrees.
>>2.2 m/s.
c)Since the velocity is constant due to the fact that there are no external forces acting in the horizontal direction, if you neglect air resistance, therefore, the horizontal velocity of a projectile is constant.

Remember these are just for your reference.You must first follow the steps as mentioned by "tiny tim" and then look up the analytical method i have solved for you.

Thanks guys for being so helpful