Projectile maths

[Pug]

If it has no mass, and no resistance, wont it keep accelerating/leave the atmosphere?

 

[Beren]

If it has no mass, and no resistance, wont it keep accelerating/leave the atmosphere?

Heh, my elementary physics is now having a slight meltdown at a particle with no mass. Does no mass mean no gravitational effect?

In terms of answering what the question wants...

The only opposing force to the projectile is mavity. mavity will only work against the movement of the bullet upwards.

What part of the problem are you struggling with?
Can you work out the upward component of the projectile?
Once you know the upward compenent do you know how to work out how long it will take for acceleration to have reduced the upward component to zero?
Once you know how long it takes do you know how to calculate how high the projectile will travel?

 

[HeX]

But no mass = no gravitational effect, so no slowing due to mavity, so it wouldn't arc and therefore wouldn't have a 'peak' height.

And no resistance = no drag.

 

[Pug]

do i get a cookie?

 

[Abraham]

But no mass = no gravitational effect, so no slowing due to mavity, so it wouldn't arc and therefore wouldn't have a 'peak' height.

And no resistance = no drag.

That bit of the question is wrong.

 

[Beren]

That bit of the question is wrong.

Really? Doesn't it actually mean that there are two genuinely correct answers to the question depending on the knowledge of the person answering the question?

As asked we don't know what speed the projectile is going ( No Units! - That would drive my old physics teacher insane!). We have to assume that they are talking about a windscreen on earth, not on a Mars or Lunar explorer as there is no statment about what gravitational force may or may not apply. We are also assuming that the projectile is leaving a piece of completely level ground at 45 degrees. Oh and I guess while I am spouting stupidities we are asuming that the body that the projectile is being fired from is locally flat enough that the curvature of the body can be discounted.

Sorry it's Monday morning and my mind is leaking pointless drivel.

 

[ntg]

<snip/snip/snip>

 

[Greenlizard0]

Who else read 'projectile vomit'?

 

[BigglesPiP]

Am I the only one who saw maths being launched at you from across the room?

 

[SlyReaper]

Assuming the speed of "4.47" is in, say, light years per decade, then its maximum height is infinite since it will have achieved escape velocity.

 

[Nimble]

Thanks for the help, having no luck tho

Tried putting the SUVAT equations into excel and i'm getting no luck.

What exactly are you having trouble with? You don't need Excel, just put in the relevent values and rearrange to solve for time and then displacement.

But no mass = no gravitational effect, so no slowing due to mavity, so it wouldn't arc and therefore wouldn't have a 'peak' height.

And no resistance = no drag.

Hmm? A photon has no mass but is affected by mavity.

 

[Inquisitor]

Hmm? A photon has no mass but is affected by mavity.

General relativity is somewhat outside the remit of this question I think

 

[Amleto]

General relativity is somewhat outside the remit of this question I think

definitely. If the question states a massless particle has non-zero y-component of velocity, and the only force that could act on the particle is mavity... the massless particle should be subject to no force whatsoever. The particle should therefore not exhibit any local maximum in displacement from it's initial position (or local minimum in speed).