Physics

[Integrator741]

Good Evening Everyone,

I think I have it right - just don't have an example to double check.

"An Object is projected vertically upwards from ground level at 49 m s^-1. Find its height after 1 s, 3 s, 5 s, 7 s, 9 s. What is its total time of flight?"

I've answered the first part of this question using "s = ut+1/2at^2" and it seems that I got that right.
Now, "when they say what is its total time of flight" do they mean both ways? Because the answer is 10s, but using "v=u+at" I get 5s. So if it is both ways then I am right, if not, I must have done something wrong.

Thank you.

 

[Gryd3]

Good Evening Everyone,

I think I have it right - just don't have an example to double check.

"An Object is projected vertically upwards from ground level at 49 m s^-1. Find its height after 1 s, 3 s, 5 s, 7 s, 9 s. What is its total time of flight?"

I've answered the first part of this question using "s = ut+1/2at^2" and it seems that I got that right.
Now, "when they say what is its total time of flight" do they mean both ways? Because the answer is 10s, but using "v=u+at" I get 5s. So if it is both ways then I am right, if not, I must have done something wrong.

Thank you.

There is no additional details regarding how it's landing. I'm sure it would be safe to assume total flight if it was shot vertically would be the time it takes to return to it's initial starting point.

 

[davenn]

and don't forget the effects of gravity acting on the object
unless the problem specifically stated to ignore it

 

[dorke]

You did fine.
Vi=initial speed
g=-9.8m/s^2 (gravity)

V(t)=Vi+g*t
at the top of the trajectory V(t)=0 ,thus
0=Vi+g*t ,so
t=-Vi/(-g) = Vi/9.8
t(TOP)=49 /9.8=5sec (time to the top)

The total time of flight is
T(Tot)= 2*t(TOP)=10sec

 

[Integrator741]

Thank you.