Show that tiem of ascent of a vertically projected body is equal to time of descent.

A : In the presence of air resistance, if the ball is thrown vertically upwards then time of ascent is less than the time of descent. R : Force due to air friction always acts opposite to the motion of the body.

A body is pushed up on a rough inclined plane making an angle 30^@ to the horizontal. If its time of ascent on the plane is half the time of its descent, find coefficient of friction between the body and the incined plane.

Read the following statements and choose the correct answer. (a) For a freely falling body the average velocity is proportional to square root of height of fall. (b) For a freely falling body the displacements in successive equal time intervals are in the ratio 1:4:9:.... (c) For a vertically projected body the displacement during last second of time of flight changes with velocity of projection. (d) For a body projected from the top of the tower the displacement of the body is negative when the body crosses the point of projection

(A) : The time of ascent for a body projected to move up a rough inclined plane is less than the time of descent. (R ) : The retardation for upward motion is more than the acceleration for down motion on rough inclined plane.

In case of an object vertically projected, show that the speed of the object upon reaching the point of projection is equal to speed of projection .

Show that if a body be projected vertically upward from the surface of the earth so as to reach a height nR above the surface (i) the increase in its potential energy is ((n)/(n + 1)) mgR , (ii) the velocity with it must be projected is sqrt((2ngR)/(n + 1)) , where r is the radius of the earth and m the mass of body.

A body of mass 5xx10^(-3) kg is launched upon a rough inclined plane making an angle of 30^(@) with the horizontal. Obtain the coefficient of friction between the body and the plane if the time of ascent is half of the time of descent.

A particle is thrown upwards from ground. It experiences a constant resistance force which can produce a retardation of 2 ms^-2. The ratio of time of ascent to time of descent 13 ( g = 10 ms^-2 )

PQ is a smooth inclined plane whose angle theta can be varied in such a way that point Q remains fixed and P can move on a vertical line PR . A particle slides from rest from point P at different value of theta time for descent from P and Q is noted. The following statement (s) is // are correct about the time of descent : A. the minimum time of descent is 2sqrt(l//g) B. the time descent is minimum continuously as theta is increased C. the time of descent decreases continuously as theta is increased D. the time of descent first decreases then increases.

A body of mass 2kg is projected from the ground with a velocity 20ms^(-1) at an angle 30^(@) with the vertical. If t_(1) is the time in seconds at which the body is projected and t_(2) is the time in seconds at which it reaches the ground, the change in momentum in kgms^(-1) during the time (t_(2)-t_(1)) is