Physics Kinematics

• Jasmine ngjiamin

  16 Sep 12, 08:45

  Hi it's me again, I couldn't solve this question even with drawing a V-T graph....Please help! Thanks!

   

  A stone is thrown vertically upwards at a speed of 60 m/s near the edge of the cliff and it falls to the bottom of the cliff after 20 seconds. What is the height of the cliff?

   

  Ans: 980 m. 

• eagle

  16 Sep 12, 09:34

  hi, is this for O levels or A levels?

  The required solution method is different for both, one uses graph and the other uses kinematic equations.

   

   

  Please follow the Guidelines for homework forum

  Thanks.

• Jasmine ngjiamin

  16 Sep 12, 09:39

  Oops sorry this is for O levels...it is actually an MCQ question and I came across this question while practising.....tried solving for 2 hours but couldnt get the correct answer :(

• hewhoshallnotbenamed

  18 Sep 12, 13:05

  hi jasmine,

  i had my Os last year and got an A2 for physics so im a reliable source! ^^

  its quite simple really, its all about gravity & air resistance. every 1 second, the speed DECREASES when thrown UPWARDS. then due to gravity pull, the speed INCREASES when it goes DOWNWARDS to the bottom of the cliff.

  check out the simple graph i've attached, hope it makes it more understandable for u.

• Jacky Woo

  18 Sep 12, 13:16

  not everyone is as smart or academically inclined as you are.

• ThunderFbolt

  18 Sep 12, 22:30

  also, it is not about air resistance. it is about gravity, as you said later. 

• hewhoshallnotbenamed

  20 Sep 12, 13:13

  @thunder: yup, slight mistake i made. edited.

  @jack: i wasnt boasting, im just saying im still relatively clear about this topic. i apologize for ur insecurity

• Jacky Woo

  20 Sep 12, 13:17

  Originally posted by hewhoshallnotbenamed:

  @jack: i wasnt boasting, im just saying im still relatively clear about this topic. i apologize for ur insecurity

  wtf is that

• hewhoshallnotbenamed

  20 Sep 12, 21:48

  in simple terms, it means I'm just better than you