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Projectile motion question

  • #1

Homework Statement


A car collides with a brick wall and comes to rest.
A parcel which was on top of the roof at the time becomes detached. It is initially traveling horizontally and it strikes the ground a distance of 12m from the point where it left the car. The parcel is initially 1.5 m above ground.

What period of time elapses before the parcel strikes the ground?

Estimate the speed of the car just before it collided with the wall?


Homework Equations


s=ut+1/2at^2
v=u+at
v^2=u^2+2as


The Attempt at a Solution


i have no idea where to start, ??
 
Last edited:

Answers and Replies

  • #2
learningphysics
Homework Helper
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You need the velocity with which the car collided?

How long does it take the parcel to fall 1.5m?

Use this time with the 12m to get the horizontal velocity.
 
  • #3
yes, thats what i initially thought as iv'e tried working this out..... the velocity was not provided..?
 
  • #4
learningphysics
Homework Helper
4,099
5
yes, thats what i initially thought as iv'e tried working this out..... the velocity was not provided..?
can you show your steps? what was the answer given?
 
  • #5
no it wasnt, i havent made any sufficient steps..
 
  • #6
learningphysics
Homework Helper
4,099
5
no it wasnt, i havent made any sufficient steps..
First step, find the time it takes to drop 1.5m.

this is the vertical direction. initial vertical velocity = 0

try to apply:

d = v1*t + (1/2)at^2

to this situation.
 
  • #7
thankyou!:smile:
 
  • #8
learningphysics
Homework Helper
4,099
5

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