The height (in meters) of a projectile shot vertically upward from a point 3 m above ground level with an initial velocity of 23.5 m/s is
h = 3 + 23.5t − 4.9t2
after t seconds. (Round your answers to two decimal places.)
(a) Find the velocity after 2 s and after 4 s.

Explanation:

As we know that the velocity of the object is given as rate of change in its position

so we will have

now we will have

so we will have

a)

at t = 2s

b)

at t = 4 s

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.