Projectiles homework Help

Ok so this is the question

1. A golf ball is struck so that its initial velocity is 30 m s–1 at an angle of 60° above the horizontal. Assume that the ground is horizontal.
(a) (i) Show that the time of flight of the particle is 5.30 seconds, correct to three significant figures.
(ii) Find the distance of the ball from its initial position when it hits the ground for the first time.

For the first on I get 5.83 seconds not 5.30, and the second one im stumped :s
I little help would be greatly appreciated, I use SUVAT for working out these projectiles, and am a little confused with the whole Vy and Vx thing.

Reply 1

joostan

13

Original post by MR CUBES

Ok so this is the question

1. A golf ball is struck so that its initial velocity is 30 m s–1 at an angle of 60° above the horizontal. Assume that the ground is horizontal.
(a) (i) Show that the time of flight of the particle is 5.30 seconds, correct to three significant figures.
(ii) Find the distance of the ball from its initial position when it hits the ground for the first time.

For the first on I get 5.83 seconds not 5.30, and the second one im stumped :s
I little help would be greatly appreciated, I use SUVAT for working out these projectiles, and am a little confused with the whole Vy and Vx thing.

Velocity is a vector.
It can be split into horizontal and vertical components, forming a right angled triangle with the total velocity as its hypotenuse.
Using some basic trigonometry (and the angle given) the vertical and horizontal components (the other two sides of the triangle) may be calculated.

Reply 2

MR CUBES

OP

I know this, just I am unsure on where I can use the Vx and the Vy in my SUVAT'S, do they just replace velocity?, and which equation would I use for finding out part B?

Reply 3

joostan

13

Original post by MR CUBES

I know this, just I am unsure on where I can use the Vx and the Vy in my SUVAT'S, do they just replace velocity?, and which equation would I use for finding out part B?

Yes the velocities replace u/v.
Do two seperate SUVATs one for vertical and one for horizontal - the first part can be done using only vertical.

Reply 4

Indeterminate

3

Original post by MR CUBES

I know this, just I am unsure on where I can use the Vx and the Vy in my SUVAT'S, do they just replace velocity?, and which equation would I use for finding out part B?

You could use

(x,y) = (u\cos \theta, u\sin \theta)t + (0,-\frac{g}{2})t^2

where x is the horizontal displacement, y is the vertical displacement and theta is the angle of projection.

You can read off the two equations.

(edited 11 years ago)

Projectiles homework Help

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