PLease show the step by step solutions:

1) The original length of a certain spring is 16 cm. The amount of work required to stretch it to a length of 20 cm is 0.05 J.What is the spring constant? When the spring is stretched to a length of 22 cm, what force is exerted by the spring?

2) A frictionless cart is released on an inclined plane whose angle with respect to the horizontal is 100. What is the speed of the cart when it has moved 2 m along the inclined surface?

3) A trunk weighing 20 N is pushed up an inclined plane whose angle is 300. The amount of work required to move the trunk a distance of 3 m along the inclined plane is 40 J. What is the efficiency of this inclined plane?

4) A heavily loaded truck is moving along a level highway at a constant speed of 96 km/h. The power output of the engine is 120 hp (1hp = 746 watts). What is the magnitude of the force required to keep the truck moving at this speed?