Asoccer ball is kicked from the ground with an initial speed of 20.1 m/s at an upward angle of 47.8˚. a player 53.0 m away in the direction of the kick starts running to meet the ball at that instant. what must be his average speed if he is to meet the ball just before it hits the ground? neglect air resistance.

3.95 m/s

Explanation:

Given

Initial velocity(u)

launch angle

Player is 53 m away

Range of projectile

R=41.02 m

so he need to run 53-41.02=11.98 m

Time of flight of projectile

T=3.03 s

thus average speed of boy

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.