A student performs an experiment in measuring the period of a simple pendulum of known length 49.0 cm. He performed five trials and measures the results(in second) to be :1.44,1.39,1.46,1.48,1.38.Calculate the % uncertainty to compare the measured value with the theoretical value.(Hint :Theoretical value=2I√l÷g, measured value=mean value)

Ablock having mass m slides down an inclined plane. the force of friction between the block and the inclined plane is f, the block's weight is m g, and the normal force is n. (a) draw a free – body force diagram showing the forces acting on the block. (b) write down all relevant newton’s equations for a given situation.

Which statement is true? a) the work done to lift an object 6 meters is greater than the gravitational potential energy it gains. b) the work required to push an object is less than the work required to pull an object the same distance. c) the work required to raise an object to a height is equal to the gravitational potential energy the object gains. d) the work done against gravity to lift an object straight up is greater than the work required to roll it up a ramp.

The reason a penny thrown straight up inside a bus will come back to your hand is that you,the bus,the air inside the bus, and the penny are all moving at the same velocity. true or false