||Homework Help||Kindergarten-University. - Page 8

Originally posted by: Angel-Jot.

Guys. The first page, third reserved post has been edited. In it i've posted everyone who has said that they can help with a certain subject. So check that if you want. Also links provided here are also posted there.

And, i can help with English, French and Canadian History if you need help. 😃

I can also help with Spanish, Math (especially Algebra and Geometry), and English. Know a little 'bout US History.

Originally posted by: akhl

@Ayeshaa,
Another way to understand part a is
3.6 * 10^2 revolutions in 1 min
Or, 3.6 * 10^2 revolutions in 60 s
Therefore, 1 revolution in 60/(3.6*10^2) s i.e. 1/6 s
Also, 4 sparks fire in 1 revolution

Therefore, in 1/6 s, 4 sparks fire
In 1 s, 4 * 6 = 24 sparks fire

Another way to understand part b is
24 sparks fire in one second.
This means after a spark has fired, 24 more sparks will fire in 1 second.
Therefore, after a spark has fired, 1 more spark will fire in 1/24 second
Therefore, time between two sparks = 1/24 second

Thanks so much for this explanation:) I get confused very easily, and then soo many questions arise in my head, so thank you very much for simplifying your words, and giving me a better understanding of how you worked this problem out:)

@Shankar

Physics Question out of Textbook:

@Ayeshaa, the correct answer is

1. The football is kicked so that the line of force of the kick passes through the CM (center of mass) of the football.

2. When the football is thrown without giving it any spin.

In these cases, the motion of the football can be simplified to the motion of its CM.


The football cannot be treated as a reference point if

either

1. the line of action of the force of the kick does not pass through the CM

or

2. a spin is given when throwing the football.


In either of these cases, the football has rotational motion (together with translational). But, to replace the football by a point, we need only translational motion because rotational motion makes no sense for a reference point.

^^ Thanks so much =)

Well it doesn't really give you much information, I think that the displacement would be 0 for both.

@Ayeshaa
Both groups have equal displacement.

Explanation: The initial position for both groups is Cape Kennedy in Florida and the final position for both is Air Force Base in California.

They have the same initial position and the same final position. Therefore, they have the same displacement.

Note: Displacement is not 0. Displacement will be 0 only if an object starts at a point and comes back to the same point. Here, the people do not come back to the same point.

^ Thanks so much, I'm seriously beginning to sort of get this =)

1. First part: 45 km. Your answer is correct. The question asks distance (not displacement), so direction is not needed.

Second part: 115 km
(Although it is correct to say 45 km from town, the question does not say from town. So better to simply give the current position in terms of marker).

2. Initial position = 260 km
Final position = 175 km
Resultant displacement = 175 km - 260 km = -85 km (Answer)
Note that negative displacement is perfectly valid.


Note:
Resultant (i.e. net or total) displacement is always final position - initial position. Therefore only initial and final positions are important. The intermediate position 150 km is not needed in the calculation.

The 135 km that you calculated is the total distance travelled by John.

Are you sure the units are km and not mi? If mi, then change units in answers to mi.