Which of the following could cause a rolling ball eventually

Which of the following could cause a rolling ball eventually come to a stop? The ball gets tired and needs a break. The net force pushing the ball forward continuously diminishes until the net force is zero and the ball stops. There is no net force acting on the ball to keep it moving. A net force acts in the opposite direction from balls motion. An airplane has a mass of 3.9*10^4kg and takes off under the influence of a constant force of 3.1*10^4N. What is the net force that acts on the plane\'s 78 kg plot? A rocket of mass 4.7*105 kg is in flight. Its thrust is directed of an angle of 55.0 degree above the horizontal and has a magnitude of 7.8*106 N. Find the magnitude of the rocket\'s acceleration.

Solution

1.

if there is no net force then ball will keep moving like this.

if force is in the direction (push) of motion then speed of ball will keep on increasing.

if force is in opposite direction then ball then linear velocity will get on decreasing and
once comes to rest.

so ANs.

A net force acts in opposite direction from ball\'s motion.

2. Using Fnet = ma

3.1 x 10^4 = (3.9 x 10^4)a

a = 0.795 m/s^2

on pilot,

Fnet = am

F = 78 x 0.795 = 62 N

3. in horizontal,

Fnet = ma

(7.8 x 10^6)cos55 = 4.7 x 10^5 a_x

a_x = 9.52 m/s^2

in vertical,

Fnet = (7.8 x 10^6)sin55 - (4.7 x 10^5 x 9.8 ) = 4.7 x 10^5 a_y

a_y = 3.79 m/s^2

magnitude = sqrt(a_x^2 + a_y^2) = 10.25 m/s^2