Calculate trajectory of projectile?

Question

i have a ball of mass 1 kg and ball is thown upwards with the force of 20 N at an angle of 45.

so how to calculate the trajectory of the projectile??

Also write the formulas to solve this question

Thanks in advance

Answer 1

I stole this off Max... :)

First, we need to know the initial velocity.

F = 20N

m = 1 kg

θ = 45°

Thrown upward with force 20 N for 1 meter?

(Use: W = 0.5mv^2, u = sqrt(2W/m) where W = Fs)

Or

Thrown upward with force 20 N for 1 second?

(Use: u = at where a = F/m)

Assumption: s = 1 m OR t = 1s?

Fx = Fcosθ

Fy = Fsinθ

F = ma

v = u + at

s = ut + 0.5*at^2

If initial s = 1 m,

W = 0.5mu^2

u = sqrt(2W/m)

u = sqrt(2*20/1)

u = sqrt(40) m/s

If initial t = 1 s,

a = F/m

u = at

u = Ft/m

u = 20*1/1 = 20 m/s

As you can see this will effect further calculation.

So, I better stop here until I am sure what the real initial velocity is.

When max height v = 0

u*sinθ - gt = 0

t = u*sinθ/g

From there you can do the rest...

But you can go to the source to see how it is calculated...

[thanks to max =P]

Answer 2

Luckily, this is not that hard, if you can make one assumption; that is that the initial force acted on the ball for 1 second.

Start with the general equations:

F=ma  and

d = (Vo)t + ½ a t²

The initial acceleration of the ball is a = F/m = 20/1 = 20m/sec².  Given that this is at a 45º angle, it will have both a "x" and a "y" component.

In the "x" direction, the initial velocity is 20 cos 45º = 14.14m/sec.

In the "y" direction, the initial velocity is 20 sin 45º = 14.14m/sec.

For the trajectory,

In the "x" direction, the formula will be:

d = 14.14m/sec x t(secs)

In the "y" direction, the formula will be:

d = 20 sin 45º (t) - 4.905 (t²)  = 14.14 (t) - 4.905 (t²) (remember, acceleration due to gravity is -9.81 m/sec² )

Answer 3

But what if the assumption for the force is done for 1 meter distance?

Anyways, thumbs up Craigory for the solution...

You are welcome muchkinhugs...