A 320 kg rocket sled can be accelerated at a constant rate from rest to 1900 km/h in 2.1 s. What is the magnitude of the required net force?

It is really hard for me right know

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?

Which property is expressed in distance units? o a. period o b. wavelength o c. speed o d. frequency