Question

Kinda confused with equations of motion on how or when to use them, how do I solve these? a)If an object is dropped from rest and falls 16m before hitting the floor, how long does it fall for? (Take acceleration due to gravity to be 10m s-2) b)In travelling the 70cm along a rifle barrel, a bullet uniformly accelerates from rest to a velocity of 210m s-1. Find the acceleration involved and the time taken for which the bullet is in the barrel.

Answer 1

Answer:

Explanation:

Analyse the situation. Make a Diagram in your brain. Make a FBD. and then solve.

a.

u= 0 m/s

s= 16m

Once you ensure all the given terms are in SI unit, apply the equations directly. Use sign convention to determine the direction of the vector.

we want time.

s= ut+1/2at²

-16= -5t²

t= √16*5

= 4√5 sec