Answer:
The periodic table illustrate some of the elements from Hydrogen to Calcium
The mass of the Book is 2.27 kg.
Answer:15.66 J
Explanation:
mass of block 
Force magnitude=7.5 N
Initial velocity =
Final velocity=
Initial Kinetic Energy=
=
Final Kinetic Energy=
=
Work Done =Final -Initial Kinetic energy=37.714-22.056=15.66 J
Answer:the velocity is zero, the acceleration is directed downward, and the force of gravity acting on the ball is directed downward.
Explanation:
When a ball is tossed vertically upwards, it reaches its maximum point. This maximum point is known as the maximum height of the ball. At this maximum height, its velocity is zero, its acceleration is directed downwards and the force of gravity acting in the ball is directed downwards towards the earth.
having to push a rough and heavy box across the floor to move it
Explanation:
Friction is not a useful force because we have to exert even more force to push a body that is rough and heavy across the floor to move it.
- Frictional force is a force that opposes the motion of a body.
- It costs more and uses more energy to push a rough and heavy box on surface because of friction.
- This wastes energy in systems that deals with pushing.
Friction is useful in that:
- the heat energy produced when two surfaces rub together is very useful.
- the friction between your feet and the floor keeping you from slipping and makes walking possible.
- the tread on tires helping the moving vehicle slow down and stop when necessary.
learn more:
Friction brainly.com/question/7174363
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