A small block with mass 0.0400 kg is moving in the xy-plane. The net force on the block is described by the potential-energy function U(x,y)=(6.00 J/m2)x2−(3.75 J/m3)y3. What are the magnitude and direction of the acceleration of the block when it is at the point (x = 0.37 m, y = 0.64 m)?

Blocks 1 and 2, with masses m₁ and m2, are placed on a frictionless, horizontal table with an ideal spring between then. The blocks are moved together, compressing the spring until it stores 87 J of elastic potential energy. When released from rest, the blocks move in opposite directions. Find the maximum speed of block 1 if m₁ = 7.63 kg and m2 = 4.18 kg. m/s V =

During a rockslide, a 390 kg rock slides from rest down a hillside that is 460 m long and 300 m high. The coefficient of kinetic friction between the rock and the hill surface is 0.24. If the gravitational potential energy U of the rock-Earth system is set to zero at the bottom of the hill, what is the value of U just before the slide?1.15×106 J How much mechanical energy is dissipated by frictional forces during the slide? What is its speed then? What is the kinetic energy of the rock as it reaches the bottom of the hill?

Consider an object of mass m = 4 kg on a frictionless table. The object experiences a repulsive force F = a/x2 + b/x, where F is in newtons and x is the position of the object relative to the origin. Write an expression for the work done by the repulsive force on the object as it moves from an initial position of x1 to a final position of x2.    If the object starts at a position of x1 = 8.5 m apart, how much work, in joules, is required by an external force to bring it to a position of x2 = 2.5 m apart when a = 19 and b = 11?    If the object starts at rest at a position x3 = 1.3 m and is released, at what speed v, in meters per second, will the object be moving when it is at position x4 = 12.5 m?