Recent content by physicsisgrea

Don't get the Chinese version! The print & paper quality are just unacceptably bad. The font size used is also much smaller.

Physics by Halliday, Resnick and Krane https://www.amazon.com/dp/0471320579/?tag=pfamazon01-20 Fundamentals of Physics by Halliday, Resnick and Walker https://www.amazon.com/dp/0470469080/?tag=pfamazon01-20 I want to know their difference. Also which one is better for an undergraduate...

The book is better called "Introduction to Wave Mechanics", not "Introduction of Quantum Mechanics". It gives almost no background of quantum physics, it is a good book though.

Goldstein is too tedious; Landau's far more interesting. but if you think Landau's too brief, then I'd recommend Taylor's Classical Mechanics.

a) you are correct, a = dv/dt, v = 0 -> a = 0 b) no such things as "component of speed" because speed is a scalar quantity c) you are correct d) you are correct it is because the origin depends on our choice e) "speed = constant" does not imply "velocity = constant". you can consider circular...

It is obvious there must be gravitational force, W, acting on the rod. The hinge can provide a supporting force, R, on the rod. In a state of static equilibrium (i.e. no translation plus rotation), the torque by the supportive force (T1) and the torque by gravitational force (T2), relative to a...

Which direction, x-or -y is the question referring?

Homework Statement Please refer to the figures. (The first one is multiple-choice, the latter is structured). Homework Equations For the first problem: u = √(2gH) x = uxsinθt + \frac{1}{2}gsinθt2 uycosθt = \frac{1}{2}gcosθt2 and maybe others u = initial velocity x = x-displacement...

Hi ! Can you show us your attempt for the problem ?

Since the acceleration is uniform, instantaneous acceleration = average acceleration. acceleration = slope of v-t graph from the graph, the slope of the graph during time = 30s to 40s is a straight line (that means the slope is not varying), that means the acceleration uniform. so the...

Well, the problem is quite easy to approach. Range is given by u^2 sin(2a) / g, where a is the projection angle. Since -1<sin a<1, the max. value for a sine function = 1. This occurs when the angle is 90 degrees or .5pi radians. So, for a fixed u: 2a = 90 a = 45 degrees.

If you are finding the final horizontal velocity: 13cos15 = vcos50 If you are finding the final vertical velocity: 13sin15 - 9.8t = vsin 50 If you are finding the velocity, it is equal to the square root of the sum of the squares of the above two results. The direction is given by tan^-1(vx/vy).

Where's the figure?

oh sorry! y = u sin 20 t - .5 gt^2 cos 30 x = u cos 20 t + .5 gt^2 sin 30 are they correct?

Homework Statement Suppose an elastic ball is set into projectile motion on an inclined plane, which makes an angle of 30 degrees to the horizontal. It is projected with an initial velocity of 5 m/s, making an angle of 20 degrees to the slope of the plane. Suppose the plane is very long, and no...