Answer:
energy is conserved
a force sets an object in motion. when the force is multiplied by the time of its application we call the quantity impulse which changes the momentum of that object. what do we call the quantity force x (times) distance, and what quantity can this change?
Average speed is defined as the ratio of total distance covered in total given time

here we know that total distance that man moved is


so total distance is



now here total time of the motion is


total time will be given as


now by above formula


so his average speed is 30 km/h
The law of gravitation states that things closer to the core of gravitation, have a larger force pulling down on them. In relation of you to your desk, you and the desk are both drawn downwards towards the center of gravity.
Top of the U ramp: potential energy is the highest, while kinetic energy is the lowest
Bottom of the U ramp(aka the curve part): potential energy is the lowest and the kinetic energy is the highest
THEREFORE, PE and KE have an INVERSE RELATIONSHIP.