A toy rocket that weights 10 N blasts straight up from ground level with an initial kinetic energy of 40J. at the exact top of its trajectory its total mechanical energy is 140J. To what vertical height does it rise?

14 m

Explanation:

Applying,

P.E = WH Equation 1

Where P.E = potential energy at the highest vertical height, W = weight of the toy rocket, H = Vertical height.

Note: At the highest vertical height, the kinetic energy is 0 J

Therefore,

Mechanical energy(M.E) = Potential Energy(P.E)

make H the subject of the equation

H = P.E/W Equation 2

From the question,

Given: W = 10 N,  P.E = 140 J

Substitute these values in equation 2

H = 140/10

H = 14 m

the answer is a. hope this .

i think the answer is a, hope this : )