Physics Ninja: Mastering Newton's Laws of Motion

This 1D example applies Newton's first law: constant velocity means net force zero. Sum forces (5 N right, 3 N left) to get F3 = -2 N (2 N left).

Explore the variety of forces that act on objects, including gravity, spring, tension, normal, friction, drag, buoyant, and thrust forces, and how they influence motion.

Learn to model tension forces in ropes and pulleys, determine their direction along the rope, and assess how magnitude depends on motion, friction, and massless rope and pulley assumptions.

Form a two-dimensional equilibrium problem for a 100-newton stoplight by drawing a free-body diagram, resolving tensions T1 and T2 into x and y components, and applying equilibrium equations to solve.

Explore Newton's third law by analyzing action-reaction pairs, where forces are equal in magnitude and opposite in direction, acting on different objects.

Analyze action–reaction pairs by examining forces on a cantaloupe, the table, and the earth, including gravity, and identify the corresponding forces on different objects using free-body diagrams.

Explore how to apply Newton's laws with 10 example problems, including tension and conceptual cases, as you read, pause to think, then watch the solutions.

use an ideal pulley with uniform tension, combine the pulley with the hanging mass, and apply Newton's first law to find F = mg/2, for 45 kg about 220.5 newtons.

Explore action-reaction pairs in Newton's third law through a free body diagram of a person and the Earth, showing equal and opposite forces and why the Earth doesn't move.

Compute the weight of a 1 kilogram object on the moon by the gravity equation, yielding about 1.6 m/s^2 and 1.6 newtons.

Case 1 shows that constant velocity requires the sum of forces on the man to be zero, so the normal force equals the weight and the scale reads mg.

Master Newton's laws by analyzing upward acceleration and apparent weight, using free-body diagrams to show how the normal force on a standing person equals m(g + a) when accelerating upward.

Explore a set of ten multiple-choice problems on contact and friction forces, and practice free body diagrams with labeled forces to reach solutions.

draw free body diagrams for the three blocks and apply action-reaction and contact-force concepts; on a frictionless table, F must exceed n1 and n2 for a common rightward acceleration.

Compute the coefficient of kinetic friction for a mass on a rough surface being pushed by an angled force at constant speed, using a free body diagram and force balance.

Learn to set up pulley problems with free body diagrams and Newton's second law, then solve for quantities; explore one- or two-spring systems to find stretch.

Learn two ways to solve a frictionless pulley problem with two masses using free body diagrams and Newton's laws; eliminate tension and apply limits to find the acceleration.

Analyze two identical springs in series supporting a 5 kg mass to find each spring's stretch and the total extension using Hooke's law and equilibrium.

Explore uniform circular motion by examining objects moving in circles with constant speed, from satellites to cars on turns, as a direct application of Newton's second law.

Explore how tension and net forces provide the centripetal acceleration v^2/r in uniform circular motion, using free body diagrams and the normal force on a track.

Draw a free body diagram, choose a radial axis toward the center, decompose forces into radial and tangential components, and apply F = ma with a = v^2/r to solve.

Set the bank angle on a frictionless curve so a car at 13.4 m/s rounds a 35 m radius, with tan theta = v^2/(g r).

Using free-body diagrams and Newton's second law on the frictionless two-block system, show that T-2 equals two-sevenths of T-1.

Rank accelerations in a two-mass Atwood machine on a frictionless pulley from greatest to least using a = (m2 - m1) g /(m1 + m2).

Compute the circular orbit speed of a satellite at altitude equal to twice the planet’s radius using Newton's law of gravitation, giving v = sqrt(G M_p /(3R)).

Apply Newton's laws to a crate pulled by a 450 N rope at 38 degrees; resolve the horizontal force and subtract 125 N friction to get 0.7 m/s^2.

Analyze a 3.7 kg mass on a 30-degree incline connected to a 2.3 kg mass via a frictionless pulley, deriving acceleration and tension using Newton's laws.

Determine the minimum weight of block c to prevent sliding with static friction 0.2; then compute acceleration when block c is lifted using kinetic friction 0.15.

Compute the edge speed of a 4.6 m radius merry-go-round (30 s period) to 0.96 m/s, then determine μs ≈ 0.02 for circular motion.