Amachine launches a tennis ball at an angle of 25° above the horizontal at a speed of 14 meters per second. the ball returns to level ground. which combination of changes must produce an increase in time of flight of a second launch?
a. decrease the launch angle and decrease the ball’s initial speedb. decrease the launch angle and increase the ball’s initial speedc. increase the launch angle and decrease the ball’s initial speedd. increase the launch angle and increase the ball’s initial speed

D. increase the launch angle and increase the ball’s initial speed

Explanation:

for a body undergoing a projectile motion ,the time of flight will be the following

t=(2usin∅)/g

t=time of flight

u= the velocity a body undergoes during the motion

g=gravitational constant(9.81m/s^2)

∅=launch angle

mathematically, as the velocity and angle of inclination increases the time of flight also increases provided that g is constant .

D. increase the launch angle and increase the ball’s initial speed

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.