Magnetic Field and Principles

  1. Magnetic field due to a wire can be calculated using the formula at a distance from the wire. 2. Water is not used in glass thermometers due to freezing and boiling points affecting measurements. 3. Magnetic recording involves encoding data using magnetic fields on a medium. 4. Magnetic materials respond to magnetic fields while non-magnetic materials do not. 5. A freely suspended magnet aligns with the Earth's magnetic field, pointing north-south. 6. Density of cooking oil = mass/volume = 450 g / 500 mL = 0.9 g/mL.

Energy Work and Power

  1. The potential energy (Ep) is expressed as Ep=mghEp = mgh where m = mass, g = gravity, h = height. 2. Work done is maximized when the force and displacement are aligned; minimized when they are opposite. 3. 1kWh=3.6MJ1 kWh = 3.6 MJ. 4. Horsepower to pump water = ( \frac{mg \cdot h}{t \cdot 746} ). 5. Height reached by boy = 300J / 75N = 4m. 6. Manometer measures pressure difference, barometer measures atmospheric pressure.

Forces and Motion

  1. Communication satellites must maintain specific speeds to stay in geostationary orbit. 2. A pencil balances well on its tip due to low base area; stability is affected by center of mass and base area. 3. Ice skates slide due to lower friction than shoes, which skid. 4. Methods to reduce friction include lubrication, surface texturing, and using ball bearings. 5. Dynamic translational equilibrium occurs when forces balance with zero net motion. 6. Moment of force, or torque, depends on magnitude of force and distance from pivot.

Orbital Mechanics

  1. Orbital speed of a geostationary satellite can be calculated using orbital radius and gravitational effects. 2. Centripetal force is given by F=mv2rF = \frac{mv^2}{r}; in moons, gravity provides the force holding it in orbit.

Motion and Inertia

  1. The direction of velocity for a whirling stone is tangential to the circle at any point. 2. To convert: a. 160 km/h = 44.44 m/s; b. 15 km/h² = 0.042 m/s². 3. Limitations of Newton's laws include applicability to non-relativistic speeds and large gravitational fields. 4. Acceleration can occur without a change in speed when changing direction. 5. Padded foam in cricket gloves absorbs impact forces. 6. Shaking a branch removes leaves due to inertia against sudden movement.

Newton's Laws

  1. Newton's second law can be expressed in terms of momentum: F=dpdtF = \frac{dp}{dt}. 2. Recoil velocity can be calculated using conservation of momentum principles.

Measurement and Theory in Physics

  1. Converting age in milliseconds and megaseconds. 2. Precision refers to repeatability; accuracy refers to correctness. 3. Scalar quantities have magnitude only; vector quantities have magnitude and direction. 4. Validity of a theory is determined by its ability to make accurate predictions. 5. Classical physics does not address phenomena at quantum scales. 6. Theory explains broader phenomena; laws are established truths. Examples: Theory - evolution, Law - Newton's laws.