Join TSR now and get all your revision questions answeredSign up now

Basic SUVAT stuff Watch

    • Thread Starter
    Offline

    2
    ReputationRep:
    A bullet is fired horizontally at a speed of 200m/s at a target which is 100m away. Ignoring air resistance calculate how far the bullet has fallen when it hits the target.

    I used
    average v=s/t
    200=100/t
    200t=100
    t=100/200
    t=0.5s

    then I said gravity was 9.81m/s/s and so i did
    t*gravity = distance travelled down
    0.5*9.81= 4.905m

    The answers said it was 1.2m travelled down. How do you get there?

    Thanks in advance
    Offline

    3
    ReputationRep:
    Where do you get your t*gravity = distance from

    s=ut +0.5at^2
    • Thread Starter
    Offline

    2
    ReputationRep:
    ooh i did t*gravity because i thought gravity = distance travelled down

    thanks : ) i forgot about the equations :/ Silly me.
    Offline

    0
    ReputationRep:
    t*gravity =/= distance

    t*a (=t*g) would be the increase in speed (or the final speed in this case, as the initial vertical speed is 0). This can be seen just by looking at units:

    Units of (t*a) = Units of t * units of a = s * m/s^2 = m/s. This is a unit of velocity.

    TenOfThem (post 2) gives you the right equation to use.
 
 
 
Poll
Would you shell out for travel insurance?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

How to use LaTex

Writing equations the easy way

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.