Yacoubb's Physics 3/4 Thread

[grannysmith]

I'm guessing the upwards force acting upon the ball is air resistance? So drag?

[alchemy]

Sorry I'm so confused :s. So the downwards force is weight (mass x gravitational field strength)?

Remember to refer to gravity as 'the acceleration due to gravity'; gravity itself is not a 'force'. Think of Newton's Second law (force is directly proportional to the product of mass and acceleration). Weight force is always 'Mass' of the object multiplied by the 'acceleration due to gravity'. Just so you understand, that's the general concept with 'weight force'. 

What is the upwards force acting on the ball?

Most likely to be air resistance for a ball which is falling down. However, as Conic said, you can negate this usually for VCE.

[Conic]

Sorry I'm so confused :s. So the downwards force is weight (mass x gravitational field strength). What is the upwards force acting on the ball?

There is usually no upwards force acting on the ball (unless there is air resistance).

[Yacoubb]

Remember to refer to gravity as 'the acceleration due to gravity'; gravity itself is not a 'force'. Think of Newton's Second law (force is directly proportional to the product of mass and acceleration). Weight force is always 'Mass' of the object multiplied by the 'acceleration due to gravity'. Just so you understand, that's the general concept with 'weight force'.

Ok thanks
So the downwards force is weight (mg) component. thanks!

[Yacoubb]

A dodgem car of mass 200kg is driven due south into a rigid barrier at an initial speed of 5.0 m/s. The dodgem rebounds at a speed of 2.0 m/s. It is in contact with the barrier for 0.20 seconds.
Calculate:
(A) the average acceleration of the car during its interraction with the barrier.
(B) the average net force applied to the car during its interraction with the barrier.

[Conic]

A dodgem car of mass 200kg is driven due south into a rigid barrier at an initial speed of 5.0 m/s. The dodgem rebounds at a speed of 2.0 m/s. It is in contact with the barrier for 0.20 seconds.
Calculate:
(A) the average acceleration of the car during its interraction with the barrier.
(B) the average net force applied to the car during its interraction with the barrier.

If you consider the original direction positive, it rebounds with a negative velocity (ie, in the opposite direction).
Its initial velocity is +5, and when it rebounds its velocity is -2. The change in velocity is 5-(-2), or 7.

a,

b,

[Yacoubb]

If you consider the original direction positive, it rebounds with a negative velocity (ie, in the opposite direction).
Its initial velocity is +5, and when it rebounds its velocity is -2. The change in velocity is 5-(-2), or 7.

a,

b,

Makes sense now. I never knew that opposite direction theory. Will keep that in mind. Thanks

[alchemy]

Makes sense now. I never knew that opposite direction theory. Will keep that in mind. Thanks

Opposite direction theory? Don't think of it like that. It's just velocity, and velocity always has a direction.

[Yacoubb]

Opposite direction theory? Don't think of it like that. It's just velocity, and velocity always has a direction.

Lmao thats just me trying to convey what I understood in my own weird lingo

[Rod]

Sorry I'm so confused :s. So the downwards force is weight (mass x gravitational field strength). What is the upwards force acting on the ball?

Also, does anyone know how I can obtain worked solutions for the Jacaranda Physics 2 textbook?

Hey Yacoubb, here are the worked solutions for this text book if you haven't found them already:

http://catalogimages.johnwiley.com.au/Attachment/07314/0731408179/JP2_3E_TSK_Part%20A.pdf

Have you liked the text book so far? I've downloaded the heinemann edition as well and I seem to like that one better than the Jacaranda.

Keep up the good work!

[alchemy]

I've downloaded the heinemann edition as well and I seem to like that one better than the Jacaranda.

Keep up the good work!

ooo..sounds sus... LOL

As far as I know, it's legal to possess an electronic copy of the book provided you have the hard copy already. Stay safe mate.

[Rod]

ooo..sounds sus... LOL

As far as I know, it's legal to possess an electronic copy of the book provided you have the hard copy already. Stay safe mate.

Well I don't have the electronic copy for jacaranda, just the hard copy. As for heinemann I did truly download it without purchasing a hardcopy version. Should I be worried??, might go to jail! ! 

[Yacoubb]

Ok I feel like I'm screwed for Physics. What do I do D: I feel like I know nothing & that's really concerning me! I've done up to chap 3 and I'm really not satisfied with my knowledge of motion. Fml! I need help! What should I do??

[Thorium]

DW Yacoubb, you will eventually grasp the concept. Personally, whenever I get baffled with anything, I just turn to  Khan Academy. You can get the app or go to his YouTube channel (I prefer the app as everything is well categorised in it, so that the users can find the video they want quicker). If you still didnt grasp the concept, dont worry again. Instead take a rest and enjoy your holiday. When the schools start, the teacher will go over everything thoroughly.(btw, I like the quote below your profile pic

[alchemy]

Ok I feel like I'm screwed for Physics. What do I do D: I feel like I know nothing & that's really concerning me! I've done up to chap 3 and I'm really not satisfied with my knowledge of motion. Fml! I need help! What should I do??

IMHO, I really think you should revise Unit 2 motion. Test your knowledge with some Year 11 motion exams. Chapter 1 in the Heinemann Physics 12 book does go over Unit 2 motion topics but not to a great depth. You might not feel like it, going back a year and all, but it's better to have that foundation first.

Option 2: If you don't believe me, try any Physics Unit 2 practice exam. PM me if you don't have any; I have quite a few. Let your performance on that be an indicator of what you need to revise from now on. Once again, there's no point in moving on when you don't understand the basics.