Physics Chapter on Newton's Laws and Friction

Newton's Laws of Motion

• Newton's first law: an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
• Newton's second law: the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. (F = ma)
• Newton's third law: for every action, there is an equal and opposite reaction.

Static Friction

• Three variables affecting static friction:
  • The coefficient of static friction (μs)
  • The normal force (Fn)
  • The force of static friction (fs)

Force to Move a Box

• To move a 150 kg wooden box on a carpeted floor with a coefficient of static friction of 0.65, the force needed to overcome static friction is (0.65 x Fn). The normal force (Fn) can be calculated using the formula Fn = mg , where m represents mass and g represents acceleration due to gravity.

Conservation of Momentum

• Total momentum is conserved in a closed system. The total momentum before an event equals the total momentum after the event.

Hockey Puck and Octopus

• A 0.115 kg hockey puck moving at 35 m/s collides with a stationary 0.265 kg octopus. They slide off together. Calculate their velocity after the collision using the law of conservation of momentum.

Effect of Increasing Force Application Time on Acceleration

• Increasing the time over which a force is applied to an object decreases its acceleration.

• This relationship is explained using the formula impulse = change in momentum (Ft = mvf – mvi). Time is a factor in this formula.

Ball Rebound Height

• A ball with a coefficient of restitution (e) of 0.84 dropped from a height of 1.5 meters will rebound to a height of 1.5 x 0.84² meters.

Angular Distance vs. Angular Displacement

• Angular distance is the total angle covered, while angular displacement is the change in angle from the starting position. They may not always be the same.

Radian Measure

• A radian is a measure of an angle equal to the ratio of the arc length to the radius of the circle.

Angular Velocity

• Calculate the angular velocity of a twirling baton that completes one revolution in 0.35 seconds.

• Angular velocity (ω) in rads/sec = (2 * π)/time = (2 * π)/0.35

Linear Distance and Rotation

• Linear distance increases as the point moves away from the axis of rotation. Angular distance is however constant.

Resultant Baseball Velocity

• Given the angular velocity and radius of rotation, use the formula relating angular velocity to tangential velocity to find the resultant velocity. The tangential velocity is directly proportional to the angular velocity. It increases with increasing distance .

Effect of "Choking Up" on a Bat

• "Choking up" on a bat (decreasing the radius of rotation) increases the resultant linear velocity of a hit ball, which increases efficiency of the bat swing. This effect, in practical terms, results in quicker bat swings with increased energy transfer to the ball. This is a result in increase energy transferring from the bat to the ball (more tangential velocity).
• The angular kinematics involves the equations of angular motion. The angular kinetics relate angular quantities to the cause of rotation, torque.

Torque

• Torque is a measure of the force that can cause rotation. Units are Newton-meters (Nm).

Types of Levers

• List and distinguish different types of levers. Compare their positions of force, fulcrum and load.

Forces Affecting Motion in Fluid

• Name three forces affecting the movement of an object in a fluid (or through a fluid). Examples include drag, lift, and thrust, as well as buoyancy.

Laminar Flow

• Laminar flow is a type of fluid flow where the fluid moves in parallel layers.

Swimming Kicking

• Besides propulsion, kicking helps swimmers maintain body position in water using propelling force from the legs.

Bernoulli's Principle

• Bernoulli's principle explains the relationship between fluid velocity and pressure. It depicts how faster moving fluids have lower pressure.

Explore the fundamental principles of Newton's Laws of Motion, static friction, and the forces involved in moving objects. This quiz covers the mathematical relationships and applications of concepts like force, mass, and momentum. Test your understanding of these key physics topics with practical examples and calculations.