Force and Motion Shopping Review 7th Grade Science

Formulas! Force = Mass x Acceleration --Measured in Newton's Momentum = Mass x Velocity --Measured in kilogram-meters per second (m/s) Weight = Mass x Gravity --Measured in Kilograms Pressure = Force/Surface Area --Measured in Newtons/kg

Forces Acting With or Upon Each Other =25N (Net Force) 30N 30N =60N (Net Force) -These forces cancel each other out. One Newton is the force required to move a one kilogram of mass 1 meter per second per second.

Friction Friction is the force that one surface exerts on another when the two rub against each other. Sliding friction- when solid surfaces slide across each other. Rolling friction- when an object rolls over a surface. Fluid friction- the friction that occurs when an object moves through a fluid. Air Resistance- The fluid friction experienced by objects falling through air

Gravity & Free Fall Gravity- is the force that pulls objects toward each other. Free fall- when the only force acting on an object is gravity. ---9.8 meters per second per second o 1st second the velocity is 9.8 m/s o 2nd second the velocity is 19.6 m/s o 3rd second the velocity is 29.4 m/s…

Forces, Mass & Weight Mass- Measure of the gravitational force which is Experienced by an object (like a rock) OR Produced by an object (such as a planet) A Measure of matter in an object Force- A push or a pull Net force is the overall force on an object after all the forces acting on it are added. Unbalanced forces will change an object’s motion. Balanced forces will not change an object’s motion. Weight- Measure of the force of gravity.

Newton's Laws of Physics I. An object at rest stays at rest. An object in motion stays in motion at the same speed and direction, unless acted upon by an outside force. II. The net force acting on an object is equal to the product of its acceleration and its mass. (F= mass x acceleration) III. If one object exerts a force on another object, then the second object exerts a force of equal strength in the opposite direction on the first object. (Equal and Opposite Reactions)

Other Laws of Physics Inertia (Law of Inertia): the tendency of an object to resist change in its motion, for example if a car stops, the objects in the car continue to move in the direction the car was moving. Law of Universal Gravitation: states that any two objects in the universe will attract each other. Gravitropism: The ability of a seedling to grow the stem upward and roots downward, no matter how the seed is placed in the soil. Terminal velocity: The maximum velocity a falling object achieves (due to it’s Mass and Gravitational effect)

Basic Guidelines of Physics As mass increases, inertia increases as well. A snowball rolling downhill As mass decreases, acceleration decreases as well. As velocity moves in one direction, acceleration moves in the same direction. Velocity and Acceleration move in tandem The force of gravity increases when the mass of an object increases. More mass of an object for gravity to attract.

To Increase Friction on a Roadway… Add sand Add salt Bigger tires Tap breaks often Newer Tires To Decrease Friction on a Roadway…. Smoother surface Bald tires Rain/water on road Ice No treads

Friction…. Sliding Friction: Solid surfaces SLIDE across each other Both SLIDING and ROLLING friction: Involve surfaces, type of friction, measured in Newtons ROLLING Friction: Rolls over a surface Forces Balanced forces: will change an object’s motion Unbalanced forces: will not change an object’s motion BOTH balanced and unbalanced forces are measured in Newtons using a SPRING SCALE.

Say WHAT?? As inertia increases, mass increases. As mass increases, acceleration decreases. As velocity moves in one direction, acceleration moves in the same direction. The force of gravity increases when the mass of an object increases.