2/12 & 2/ th Grade Agenda Learning Objective: Learn about Gravity Collect HW: Reading & Notetaking p.175 – 176 Textbook Reading p HW: Reading & Notetaking p.177 – 178 Reminder Science Fair Board due 2/24 (50 Points)

Daily Reflection Prompt: Write 3 facts about friction

The force that one surface exerts on another when the two rub against each other is called … F________ riction

Friction act in a direction O_________ to the object’s direction of motion. pposite

The strength of the force of friction depends on two factors Type of surfaces involved How hard the surfaces push together

How is friction useful in helping you walk? Without friction your shoes would only slide across the floor, and you would never move forward.

What is static friction The friction that acts on objects that are not mov______ is called static friction. Because of static friction you must use ext_____ force to start the motion of stationary objects. ing ra

What is sliding friction Sliding friction occurs when two solid surf______ slide over each other. When you stop a bicycle with hand brakes, sliding friction is stop______the bike. ace ping

What is rolling friction When an object rolls across a surf______, rolling friction occurs. Engineers use ball bearing to reduce the friction between the wheels and the skate________ ace board

What is rolling friction Fluids, such as water, oil or air are materials that flow eas______. Fluid friction occurs when a solid object moves through a fluid. Fluid friction is usually less than sliding fric______. ily tion

For an object to stay in motion, a F_____ has to act on it. orce

The tendency of an object to resist change in its motion is called I________ nertia

Which will fall faster? Will a lighter object fall faster or a heavier object? Will a piece of paper fall faster or a text book? Why? Lets try.

Which will fall faster? Will a penny fall faster or stack of a3 pennies? Why? Lets try.

The force that pulls objects toward each other is called G______ ravity

If two balls with different masses are dropped to the ground in a vacuum, would they fall exactly the same rate? Yes

The amount of matter in an object is called M_____ ass

Why does a leaf fall more slowly than an acorn? Because of air resistance. In a vacuum, both would fall at the same speed