A kangaroo can jump over an object 2.50 m high. (a) Considering just its vertical motion, calculate its vertical speed when it leaves the ground. (b) How long a time is it in the air?

a) Vertical speed when it leaves the ground is 7 m/sb) Kangaroo is in air for 1.43 seconds.

Explanation:

a) We have equation of motion v² = u² + 2as

Initial velocity, u = ?

Acceleration, a = - 9.81 m/s²

Final velocity, v = 0 m/s

Displacement, s = 2.50 m

Substituting

v² = u² + 2as

0² = u² + 2 x - 9.81 x 2.50

u = 7 m / s

Vertical speed when it leaves the ground is 7 m/s

b) We have equation of motion s = ut + 0.5 at²

Initial velocity, u = 7 m/s

Acceleration, a = - 9.81 m/s²

Displacement, s = 0 m - - - Time is calculating for returning to ground

Substituting

s = ut + 0.5 at²

0 = 7 x t + 0.5 x - 9.81 x t²

t = 1.43 seconds

Kangaroo is in air for 1.43 seconds.