Question

A projectile is launched with an initial speed of 40.0 m/s at 60.0 degrees above the horizontal. It hits the ground at the same height it was launched from. Neglect air resistance.

a) What is the projectile's smallest speed as it moves through air?

b) What is the projectile's smallest magnitude of acceleration as it moves through air?

c) What is the projectile's speed 1.00 second after launch?

d) What is the magnitude of the projectile's displacement 1.00 second after launch?

Answer 1

a) The smallest speed of the projectile occurs at the maimum height where only the horizontal components of the velocity is left. Since horizontal component of the projectile is constant throughout the motion, it is equal to

b)The acceleration of of the projectile is constant thruoghout the motion because there is only force, i.e, gravity acting on the body, and the variation of acceleration due to gravity is taken as constant for such a small height range. Therefore, the magnitude of acceralation is constant that is

c)In a projectile motion, the horizontal component of velocity is always constant that is

the vertical compenent changes as acceleration due to gravity is acing on the body, and the given time is less than the half of time of flight so the body decelerates. Therefore horizontal component of velocity u after one sec is

Therefore, velocity after one second of launch is

d)

vertical displacement:

Horizontal displacement:

total displacement