A wheel stays in the upright position while rolling,whereas it falls from its upright position when stationary .Why?

A transverse harmonic wave on a string is described by y(x. t) = 3.0 sin (36 t + 0.018 x + (pi//4)) where x and y are in cm and tin s. The positive direction of x is from left to right. Is this a travelling wave or a stationary wave ? If it is travelling, what are the speed and direction of its propagation ?

A stone is allowed to fall from the top of a tower after 6 s.Find : its position after 4 s.

When a bucket full of water is rotated,water does not fall from it.Why?

A point P lying inside the curve y = sqrt(2ax-x^2) is moving such that its shortest distance from the curve at any position is greater than its distance from X-axis. The point P enclose a region whose area is equal to

A particle suspended from a fixed point, by a light inextensible thread of length L is projected horizontally from its lowest position with velocity (7gL/2)^(1/2) . The thread will slack after swinging through an angle theta , such that theta equal

Constant forces 2 hat i-5 hat j+6 hat k and -hat i+2 hat j-hat k act on the particle. Determine the work done when the particle is displaced from a point A with position vector 4 hat i-3 hat j-2 hat k to a point B with position vector 6 hat i+hat j-3 hat k .

While pushing a heavy box from one place to another in his house, Naresh noticed that it was difficult to take a stationary box from its resting position to moving position but it was easy to move that box with that speed. Why was it so?

A girl of 40 kg mass jumps with a horizontal velocity of 5ms'1 on a stationary trolley. The wheels of the skate are frictionless. What will be the velocity of the girl in the position of start of the trolley. Suppose no unbalanced force is acting in the horizontal direction.(mass of trolley is 3 kg)

Take a clock and fix its minute hand at 12. Record the angle turned through by the minute hand from its original position and the time that has passed, in the following table : What do you observe about T and A ? Do they increase together ?