A streamlined object is thrown straight upward. Its kinetic energy at the instant it leaves the thrower’s hand (the zero height) is 20 J

Question

. Fill in the blanks. A streamlined object is thrown straight upward. Its kinetic energy at

         the instant it leaves the thrower’s hand (the zero height) is 20 J. What is the numerical

         value of its:

          a) potential energy at the instant it leaves the thrower’s hand?________________

          b) total mechanical energy at the instant it leaves the thrower’s hand?______________

          c) potential energy half way to the maximum height?_______________

          d) total mechanical energy at the maximum height?__________________

          e) kinetic energy when it’s caught (at the same height as t which it was

             released)_______________

          f) potential energy when it’s caught?_______________

          g) total mechanical energy when it’s caught?______________

Answer 1

(a) zero because height is zero

(b) potential + kinetic = 20 J

(c) Half of the kinetic energy will have changed to potential so 10 J

(d) 20 J (assuming energy conservation and no loss due to air resistance)

(e) 20 J (assuming energy conservation)

(f) zero because height is zero

(g) 20 J