Skating Flashcards
Why does a stationary skater remain stationary?
A body at rest tends to remain at rest. This is known as inertia.
Why does a moving skater continue moving?
A body in motion tends to remain in motion. This behavior is the second half of inertia.
Newton’s first law is?
An object that is free of external influences moves in a straight line and covers equal distances in equal times.
An object that is free of external influences moves at a constant velocity. It covers equal distances in equal times. The direction is unchanged.
An object that is not subject to any outside forces moves at a constant velocity.
A rotary lawn mower spins its sharp blade rapidly over the lawn and cuts the tops off the grasses. Would the blade still cut the grasses if they weren’t attached to the ground?
Yes, the grass has inertia. It tends to stay at rest, whether or not it is attached to the ground. The blades are moving at a very high seed.
Why does a skater need ice or wheels to skate?
Real-world complications usually mask inertia. Solution: minimize or overwhelm complications.
Position
An object’s location, distance and direction from a reference.
Velocity
Its change in position with time, speed and direction of motion.
Force
A push or pull, amount and direction of the push or pull.
Net force
Vector sum of all forces on an object.
How does a skater start or stop moving?
A net force causes the skater to accelerate.
Acceleration
Change in velocity with time. Another vector quantity, rate and direction of the change in velocity.
Mass
Measure of object’s inertia
Newton’s Second Law
An object’s acceleration is equal to the net force exerted on it divided by its mass. That acceleration is in the same direction as the net force.
A force causes an acceleration
Force and acceleration are in the same direction
An acceleration means the velocity is changing
