Question

If air resistance is taken into consideration when the body is projected at an angle then which of the following is correct

1. The time taken to move to Maximum height if greater than the time taken to move from Maximum height to the ground

2. At maximum height acceleration of projectile is greater than g

3. Maximum height decreases

4. Speed of the projectile when it hits the ground is equal to the speed of projection

Answer 1

we know that the air resistance like friction always oppose the motion.
when going upwards the gravity and air resistance both oppose the motion and while descending gravity supports the motion and air resistance oppose the motion
let us consider each options 1 by 1
1)as both gravity and air resistance oppose the ascending the time of ascending will be lesser
and as air resistance oppose the descending the time to reach the ground will be more
this is contrary to the 1st option.so this is wrong
2)at maximum height the projectile is at rest so air resistance has no impact in its acceleration and hence its acceleration is g hence this option is also wrong
3)as air resistance oppose the asceding the maximum height reached will be lesser and hence THIS OPTION IS WRIGHT
4)Then energy is lost as the ball moves up and comes down due to friction with air which will resist the motion. Thus the ball will come down with a velocity less than the velocity with which it was projected and so this option is also wrong