40) Find the net force produced by a 30-N force and a 20-N force in each of these cases: (a) Both forces act in the same direction.

40) Find the net force produced by a 30-N force and a 20-N force in each of these cases:
(a) Both forces act in the same direction.
(b) The two forces act in opposite directions.
45) A horizontal force of 120N is required to push a bookcase across a floor of constant velocity
(a) What is the net force acting on the bookcase?
(b) How much is the friction force that acts on the sliding bookcase?
(c) How much friction acts on the bookcase when it is at rest on a horizontal surface without being pushed?
48) (a) Show the average speed of a tennis ball is 48 m/s when it travel the full length of the court, 24m in 0.5 s.
49) (a) Show the average speed that the average speed of Leslie is 10 km/h when she runs to the store 5km away in 30min
50) (a) Show that the acceleration is 7.5 m/s for a ball that starts from rest and rolls down a ramp and gains a speed of 30 m/s in 4s.