Tamara exerts a force downward on a chair by sitting on it. Which of the following statements best explains why the chair does not move downward?
A The chair exerts an upward force that is greater than the force exerted by Tamara
B
The floor exerts an upward force that is greater than the force exerted by Tamara
The chair exerts an upward force that balances the downward force exerted by Tamara
D
The floor exerts an upward force on the chair that balances the downward force exerted by Tamara

Aballoon is rising vertically upwards at a velocity of 10m/s. when it is at a height of 45m from the ground, a parachute bails out from it. after 3s he opens his parachute and decelerates ata a constant rate 5m/s.when. (a) what was the height of the parachutist above the ground when he opened his parachute? (b)how far is the parachutist from the balloon at t=3s? (c)with what velocity does the parachutist hit the ground? (d)after how long does the parachutist hit the ground after his exist from the balloon?