A 25 kg child plays on a swing with support ropes that are 2.2 m long. A friend pulls her back until the ropes are 42.2 from the vertical and releases her from rest. What is the potential
energy for the child just as she is released compared with the potential energy at the bottom of
the swing?
A. 177 J
B. 140 J
O
C. 539 J
D. 160 J
NEED ANSWER NOW

the velocity you are looking for is made up of two parts: horizontally velocity, vh, and its vertical velocity, vv. the actual velocity of the ball will be these two parts added together, and because velocity is a vector then they will need to be added vectorially.  

neglecting air resistance etc etc.,  

the horizontal velocity component will be constant (because there is no accelerating force in the horizontal direction.  

vh = 8 ms-1  

the vertical velocity component has an accelerating force: 'g'.  

using v = u +at where a = g = 9.81 ms-2.  

the vertical component of velocity, vv = 0 + gt = vv =9.81 x 2  

vv = 19.62 ms-1 . the zero appears because the virtical component of velocity at time t=0 is zero. remember, the ball was thrown horizontally.  

how fast it will be moving (it actual path (being a parabola )) will be the vector sum of these two.  

adding vectorally gives: -  

v = sqr root (8^2 + 19.62^2) = sqr root(64+384.9) = 21.18 or 21.2 ms-1

prolly a beacuse the momentuem the car has increases while going down hill

thermal energy is the answer