Answer:
Part a)

Part b)
Ball thrown downwards =
Ball thrown upwards =
Part c)

Explanation:
Part a)
Since both the balls are projected with same speed in opposite directions
So here the time difference is the time for which the ball projected upward will move up and come back at the same point of projection
Afterwards the motion will be same as the first ball which is projected downwards
so here the time difference is given as



Part b)
Since the displacement in y direction for two balls is same as well as the the initial speed is also same so final speed is also same for both the balls
so it is given as




Part c)
Relative speed of two balls is given as


now the distance between two balls in 0.8 s is given as



Answer:
B, it includes a control group and an experimental group.
Answer:
156.96 N
Explanation:
F=ma where m is the mass and a is acceleration
Substituting 16 Kg for m and 9.81 m/s2 for g then
F=16*9.81= 156.96 N
Answer:
The net force applied to the car is zero.
Explanation:
We are given that a car is moving to the left with constant velocity.
When the car moving with constant velocity
Then, the final velocity=Initial velocity
Change in velocity=Final velocity- initial velocity=0
When change in velocity is zero then , acceleration of car

When acceleration is zero then, By Newtons second law

The net force applied on the car will be zero.
Option C:The net force applied to the car is zero.