Phyisical Science Newtons Laws Flashcards
Inertia
The tendency of an object to resist changes in its velocity
Friction
A force that opposes motion, resulting in the contact of two surfaces
Kinetic friction
Friction that opposes motion once the motion has already started
Static friction
Friction that opposes the initiation of motion
State newtons three laws of motion
1st law: an object in motion (or at rest) will tend to stay in motion (or at rest) until it is acted upon by an outside force
2 law: when an object is acted on by outside forces, the total force is equal to the mass of the object times the resulting force
3rd law: for every action, the is an equal and opposite reaction
In space there is almost no air, so there is virtually no friction. If an astronaut throws a ball in space with the initial velocity of 3.0 meters per second to the west, what will the balls velocity by in a year? Assume there are no nearby planets,
Newton’s first law of motion tells us that object will not change in velocity until acted on by an outside force. Often this force is friction. In this problem, once the ball is thrown, no forces are operating on the ball. Thus in a year, the velocity will still be 3.0 meters per second to the west.
A boy is running north with s beanbag in his hand. He passes a tree and at the moment he is beside a tree, he drops the beanbag. Will it land next to the tree? If not, will it be north or south of the tree?
The beanbag will not fall next to the tree. Instead it will fall north of the tree. This once again an application of Newton’s first law. While it is the boy’s hand, the beanbag has a velocity of going north. This as it falls, it will travel north. When it land it will be north of the tree. In fact, ignoring air resistance, when it hits the ground, it will be right next to wherever the boy is at the instant, because it will be traveling north with the boys velocity.
The boy is running, but now his friend stands beside the boy with the beanbag. As the boy runs by, he barely taps the bean bag, causing it to fall out of his friends hand. Will the beanbag fall next to the tree or will it fall north or south of tree?
The bean bag will fall next to the tree. In this case the bean bag has no initial velocity. It is at rest will the boy standing next to the tree.
It is a shocker is driving down the road. Many boxes why piled on the back of the car, evidence of shopping activity. Suddenly, the shopper must hit the brakes to avoid a collision. Will the boxes be slammed further back, or will they slam into the front seat where the driver can feel them?
Boxes will slam into the front seat. The boxes that have the same velocity as the car. When the car stopped, they continue to move with the same velocity this make them move forward wrong with the car, swimming then.
When roads get wet, they can be slick. Obviously, the friction between the car’s tires and the road decreases when the road gets wet. Why?
The water fills in the grooves of the road, reducing how close the tire molecules can get to the road molecules.
