You throw a 3.00-n rock vertically into the air from ground level. you observe that when it is 15.9 m above the ground, it is traveling at 25.7 m/s upward.

a)use the work-energy theorem to find the rock's speed just as it left the ground.

b)use the work-energy theorem to find its maximum height.

a) u = 31.197 m/s

b)

Explanation:

given,

weight = 3 N

mass = 3/ 9.81 = 0.305 kg

h = 15.9 m

velocity at which it is traveling upward = 25.7 m/s

a) using work energy principle

u = 31.197 m/s

b) At maximum height

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.