Help with Physics!!!

[atom]

Please help me with this physics question:

A student whirls a rubber weight on the end of a string in a horizontal clockwise circle at a constant speed of 6.0 m/s. From an instant when the stopper is moving in a northerly direction, find its change in velocity after moving around one-ninth of a turn.

Thanks in advance

[Aurelian]

Consider the two instances between which we're considering the change in velocity.

The first instance the speed is 6.0 m/s, and the direction is northerly.

The stopper then moves around one-ninth of a turn - i.e., 20 degrees. The speed is still 6.0 m/s. We therefore have two vector quantities. Bring them together, and use trig to find the change in velocity.

I'll admit this is a little unintuitive, which is why I wont continue the question to completion in case I misplace the angle when setting up my vector diagram. Usually any question like this will be such that the two instances are at right angles to each other, and so it's simple pythagoras and relatively easy to determine; I doubt you'd see this kind of question on any VCAA endorsed assessment.

Sorry I can't conclude the question (someone with spesh knowledge might be more helpful) but I hope this points you in the right direction.

[rife168]

Ok, I just had a try, my working out is attached.
Sorry if it's a bit messy.. Also, I have worked from right to left for some reason, so the diagram on the right is what I started with, then I resolved the vectors into a triangle and used the fact that

Do you know what the solution is? I could be completely wrong, but that is how I would generally go about it.


edit: Bearing should be
oops -.-

[atom]

I've got the answer here, but it's a little different from yours. Look at the attached picture.

[rife168]

I've got the answer here, but it's a little different from yours. Look at the attached picture.

Yeah how clumsy of me! Just a mistake with my bearings -.- I don't use them very often.
That is also a much faster and efficient way of solving the problem, it is a more geometric solution than mine.

[yawho]

An inclined plane question. A 1 kg object at rest on an inclined plane. Find the magnitude and direction of the reaction force of the inclined plane on the object.

[paulsterio]

An inclined plane question. A 1 kg object at rest on an inclined plane. Find the magnitude and direction of the reaction force of the inclined plane on the object.

Direction is perpendicular to the plane.


I can't actually work it out, because you didn't include the angle.

[Bhootnike]

i hope im right haHA

[yawho]

i hope im right haHA

What is the answer?

[Phy124]

i hope im right haHA

What is the answer?

To calculate the answer you need to give the angle at which the plane is inclined to the horizontal. That is in the equation.

[yawho]

i hope im right haHA

What is the answer?

To calculate the answer you need to give the angle at which the plane is inclined to the horizontal. That is in the equation.

No angle is given in the assignment.

[paulsterio]

An inclined plane question. A 1 kg object at rest on an inclined plane. Find the magnitude and direction of the reaction force of the inclined plane on the object.

Do you know the co-efficient of friction then? There has to be more information that what you've given us.

[Bhootnike]

i hope im right haHA

What is the answer?

Well,  you said reaction force,  so From the diagram,  i guess reaction force refers to the normal reaction force,  which is 10sinTHETA,  and  you say that there is no angle so maybe it's just that? 

[yawho]

Another question: A 0.5 kg book resting on a horizontal table has a weight force acting on it. Name the reaction force to this weight force in Newton's third law.

[rife168]

Another question: A 0.5 kg book is resting on a horizontal table has a weight force acting on it. Name the reaction force to this weight force in Newton's third law.

Are these questions looking for a qualitative or quantitative answer? What is the nature of some other questions that are on the same page/assignment?