Arollercoaster starts at a height of 30m above the ground. at the bottom of a loop. the rollercoaster is at a height of 10m. approximately, how much gravitational potential energy is lost by a 75kg rider?
a. 19.6 joules. eliminate.
b. 1470 joules.
c. 14,700 joules
d. 22,050 joules

Afaulty model rocket moves in the xy-plane (the positive y direction is vertically upward). the rocket's acceleration has components ax(t) = ? t2 and ay(t) = ? ? ? t, where ? = 2.50 m/s4 , ? = 9.00 m/s2 , and ? = 1.40 m/s3 . at t = 0 the rocket is at the origin and has velocity ~v0 = v0x ? i + v0y ? j with v0x = 1.00 m/s and v0y = 7.00 m/s. (a) calculate the velocity and position vectors as functions of time. (b) what is the maximum height reached by the rocket? (c) sketch the path of the rocket. (d) what is the horizontal displacement of the rocket when it returns to y = 0?