Question

An object is thrown vertically upward from the ground at 30m/s. What is the displacement after 4sec? What is the velocity after 4s? What is the maximum height it attains? What is the time of flight?​

Answer 1

Answer:

time taken(t) =4 sec

Initial velocity (u)=30 m/sec

final velocity (v)=0 m/sec

acceleration due to gravity (g)=  -9.8 m/sec^2

height or distance travelled (h)=?

total time in air(2 t)=?

we know ,

v^2 = u^2 +2 gh

or , 0^2 =30^2 +2*(-9.8) h

or, 0-900= -19.6

or,h=900/19.6

or,h=45.96 m

Again,

2 t =2*4 sec

    = 8 sec

therefore the object reached 45.92 m high and 8 sec was the time taken to come to its initial place