# A Couple of Conceptual Questions Need help

1. Sep 24, 2005

### Karma

Thank you.

Consider a particle moving in a straight line. Does a Large change in speed always lead to a large acceleration? Explain.

For a car travelling at a given speed, there is corresponding stopping distance associated with that speed. The stopping distance is the the distance the car travels while the brakes are being applied until the car comes to a complete stop. If the initial speed of a car is doubled, by what factor does the stopping distance increase? Assume that the tires of the car always provide the same stopping acceleration, regardless of speed (a good approximation).

A book is dropped from rest and a bullet is fired from a gun horizontally (with a very high velocity) at the same time and at the same height. Both objects will hit the ground at the same time. Provide an explanation of why this must be true.

If the average velocity of a particle is Zero in some interval, what can you say about the displacement of the particle for that interval.

If you know the position vectors of a particle at two points along its path and know the time it took to get from one point to the other, can you determine the particles instantaneous velocity? its average velocity? Explain.

If a Rock is dropped from the top of a sailboat's mast, will it hit the deck at the same point whether the boat is at rest or in uniform motion at a constant velocity?

2. Sep 24, 2005

### Päällikkö

3. Sep 24, 2005

### Karma

i dont want the answers i just want help how to start the questions, and tips that will help me achieve the answers

4. Sep 24, 2005

### Päällikkö

Well, here's some short tips:

1. $$a_{avg} = \frac{\Delta v}{\Delta t}$$ if $\Delta v$ is large, must $a$ be large?
2. $$x = x_0 + v_0t + \frac{1}{2}at^2$$
$$v = v_0 + at$$
3. Vectors can be divided into components.
4,5. Definition of velocity (and avg. velocity)
6. Inertia