A 1.0 kg cart moves frictionlessly along a straight track. Its potential energy U(x) at various positions x is given in the table.
x (m): 0 0.50 1.0 1.5 2.0
U (J): 8.0 4.5 2.0 4.5 8.0
The cart is released from rest at x = 0. At which listed position is its speed greatest?
a) 0.50m
b) 1.0m
c) 1.5m
d) 2.0m