Multi choice Question 1...lame.. (1 Viewer)

[xprshn]

Sorry might be lame but, is the answer A or B for Question 1?
People are saying B (initial velocity), but why isn't it A (time of flight)?

 

[fush]

i put down A, but heaps of ppl reckon B..it was a shit question, i mean both can be right, right?

 

[gordo]

it is time of flight

if initial veloctiy is the only one that is different, that means time of flight was the same for both, then the max heights wouldn't be the same

... i think?

 

[xprshn]

Yeh i put A. Lame question.

People who got B please explain?..

 

[fush]

yes gordo! i remember now, i think A is right i did the same reasoning

 

[ShaunSmith]

initial velocity is different not time of flight, for one angle is different and two if the initial velocity is the same time of flight is the same

 

[ShaunSmith]

so yeah i got B, is that what i said?

 

[fush]

no, if inital velocity is the same then time of flight is only the same if the angle are the same, but it wasnt

 

[gordo]

the time can be different if the intial velocity is the same...
if u shoot it straight up at 20 m/s it will take longer than if u shoot it at 1 degree above the horizontal at 20 m/s...

but good try

 

[fush]

exactly gordo

 

[BillyMak]

The answer is most definately B. Time of flight is not changed, since it reaches the same max. vertical displacement. Vertically, the initial velocity is the same, but horizontally, the velocity is increased in the second throw, meaning that the initial velocity is changed.

 

[BillyMak]

the time can be different if the intial velocity is the same...
if u shoot it straight up at 20 m/s it will take longer than if u shoot it at 1 degree above the horizontal at 20 m/s...

but good try

Remember velocity is a vector, meaning that if you change the direction you are in fact changing the velocity.

 

[gordo]

Vertically, the initial velocity is the same, but horizontally, the velocity is increased in the second throw, meaning that the initial velocity is changed.

not if the angle of projection is different, then veritcally the initial velocity is different

 

[gordo]

they might cut that question out though
sometimes they cut questions out that are ambigious
i bet half the state just guessed that first one

 

[moony412]

It is B - time of flight is not different

The answer is B.

Rember that projectile motion can be seperated into both the horizontal and vertical components and in analysing only the vertical component, they are identical.

Both the balls are projected at defferent angles so in order for the vertical compnents of both motions to be the same, the initial velocity must be different because if both initial velocities were the same then the vertical displacement would be different.

Hope this helps

 

[BillyMak]

I'd be willing to bet any amount of money that the answer is B.

 

[Xayma]

They reached the same max height. Therefore their vertical velocity is equal and hence the time of flight is the same (use delta y=0). However, their horizontal velocities are different.

 

[BillyMak]

The answer is B.

Rember that projectile motion can be seperated into both the horizontal and vertical components and in analysing only the vertical component, they are identical.

Both the balls are projected at defferent angles so in order for the vertical compnents of both motions to be the same, the initial velocity must be different because if both initial velocities were the same then the vertical displacement would be different.

Hope this helps

Both balls aren't necessarily projected from a different angle, it is just that the horizontal component of the second throw is greater than that of the first, so it has a longer range.

 

[BillyMak]

Ok. I got a smart kid to agree with me. Case solved

 

[gordo]

if they both reach the same max height and u look at the vertical component alone, then obviously they both have the same time of flight

sorry i only looked back over the question and realised my answer was B