• Best of luck to the class of 2024 for their HSC exams. You got this!
    Let us know your thoughts on the HSC exams here
  • YOU can help the next generation of students in the community!
    Share your trial papers and notes on our Notes & Resources page

Q- Application of calc to phys world. (1 Viewer)

imoO

Member
Joined
Apr 6, 2008
Messages
302
Gender
Male
HSC
2009
Could someone explain to me how to do questions 9 and 10, or Ex 19(c) in the two unit fitzpatrick book?

I'm not sure how to separate the acceleration and velocity :S

Thanks in advanced.
 

~caramello~

Member
Joined
Dec 21, 2008
Messages
133
Gender
Male
HSC
2009
9) its projected at 30m/s (starts off at 30m/s) and decelerates at 10m/s^2 (slows down 10m/s every second). so the equation for the velocity should be
30-10t where t is the number of seconds.

b) and to find the equation of h, it is asking for the equation of displacement.
hence u integrate the velocity (30-10t)

c) the greatest height reached would be the time when velocity = 0 (projected up, slowing down every second until it reaches 0, then acclerates back downwards). so 30-10t=0. You now get the time when it reaches max height. You just sub it in the equation for height.

d) time taken for it to reach point of projection is when displacement = 0 (when it returns to its starting position)

question 10 is very similar. hope it helps =]
 

imoO

Member
Joined
Apr 6, 2008
Messages
302
Gender
Male
HSC
2009
Oh okays, thanks.

But how do you go about finding the equation? Is the velocity always constant and the acceleration has one power of 't'?

I'm quite confused :S
 

~caramello~

Member
Joined
Dec 21, 2008
Messages
133
Gender
Male
HSC
2009
umm.. no. velocity is not constant. It starts off at a constant rate and changes every second (could be due to gravity/air resistance etc).
I'm not that gud at explaining but here goes...

ok..velocity is the speed at which something is moving. when u throw a ball up, it goes up, slows down, stops at the max height and comes back down. so during all the time the speed of the ball is changing.

acceleration is the RATE at which the speed is changing (hence dv/dt, we differentiate the velocity equation to get acceleration). It is how much the object speeds up or slows down. In this case acceleration is constant. ( rate at which the object changing speed is -10m/s)

well..hope that helps..
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top