A wooden block of mass 0.60 kg is on a rough horizontal surface. A force of 12 N is applied to the block and it accelerates at 4.0 m.s^–2. What is the magnitude of the frictional force acting on the block?
A 2.4 N
B 9.6 N
C 14 N
D 16 N
A horizontal force of 90N is used to push a box across a horizontal floor. The frictional force on the box is 50N.
What is the gain in kinetic energy of the box when it is moved through a distance of 6.0m?
A 240 J
B 300 J
C 540 J
D 840 J
A positive charge experiences a force F when placed at point X in a uniform electric field. The charge is then moved from point X to point Y. Distances r and s are shown on the diagram. What is the change in the potential energy of the charge?
A decreases by Fs
B increases by Fs
C decreases by Fr
D increases by Fr
A submarine is in equilibrium in a fully submerged position. What causes the upthrust on the submarine?
A The air in the submarine is less dense than sea water.
B The sea water exerts a greater upward force on the submarine than the weight of the steel.
C The submarine displaces its own volume of sea water.
D There is a difference in water pressure acting on the top and bottom of the submarine.
