Answer:
3136
Explanation:
because you multiply 780 by 4 because if it has a constant speed meaning it will not change speed then you multiply it by 4 because it says in 4 hours ( I hope this helped)
Answer:
Friction produces unnecessary heat leading to the wastage of energy. The force of friction acts in the opposite direction of motion, so friction slows down the motion of moving objects. Forest fires are caused due to the friction between tree branches. However, friction can also cause problems in a car. Friction between moving engine parts increases their temperature and causes the parts to wear down. Friction can be both harmful and helpful, so it may be necessary to decrease or increase friction.
