Question

An object is thrown from the ground level into the air with a speed of 20 m/s. What is its speed when it hits the ground? (think about whether speed is a scalar or vector) and what is the objects total time in the air in seconds?

HELP MEEEEE! pleasee!!

Answer 1

20 m/s, vector quantity & 49s

Step-by-step explanation:

Using the third equation of motion

`v ^(2) = u ^(2) + 2as`

a = g [gravity] = ~9.8 m/s^2 or 49/5 m/s^2

• v^2 = u^2 + 2gs
• v^2 = 20^2 + 2(9.8)(0)... 0 because the object has landed onto the ground, so S (displacement) = 0
• v^2 = 400
• v = √400
• v = 20
• 20 m/s [vector quantity - goes in a rectilinear motion with a certain direction at certain time intervals]

TO FIND TOTAL AIR TIME:

`v = u + at`

• v = u + at
• 20 = 20 + 49/5 x t
• 20 = (20 + 49)/5t
• 20 = (100+49t)/5
• t = (20x5)/(1x100x49)
• t = 49
• 49s