PHY 101 Mock Test 1

This is the definition of a perfectly elastic collision.

With negligible external torque, L = Iω is constant. Decreasing I forces ω to increase to keep the product constant.

W_net = ΔKE. This is a fundamental theorem derived from Newton’s second law, linking forces (via work) to changes in motion (via kinetic energy).

This principle asserts that the fundamental laws of motion are invariant (take the same form) for all observers moving with constant velocity relative to each other.

An event is a fundamental concept defined by its spatial coordinates (x, y, z) and its time coordinate (t).

When vectors are opposite (180°), they subtract. The resultant magnitude is |A – B|, which is smaller than when they are at any other angle

This is a common point of confusion. The two forces are an interaction pair between two different bodies, so they do not cancel for a single body.

Multiplying by a negative scalar (-2) scales the magnitude by 2 and reverses the direction by 180 degrees.

Rotational KE = (1/2)Iω². KE is proportional to ω², so doubling ω increases KE by a factor of 2² = 4.

By definition, the normal force is the component of contact force perpendicular (normal) to the surface. Its magnitude depends on the situation.

The center of mass of any system under the influence of a uniform gravitational field follows the simple parabolic trajectory of a point mass.

A fundamental principle is that all terms in a valid physical equation must have the same dimensions. Dimensional analysis verifies this consistency but cannot determine dimensionless constants.

For kinetic and maximum static friction, the force depends on the normal force and the coefficient of friction, not on the apparent area of contact.

This is the Law of Conservation of Linear Momentum: If ΣF_ext = 0, then ΔP_total = 0.

The ball has the train’s initial horizontal velocity relative to the ground. Under gravity alone, it follows projectile motion (a parabola) as seen by the ground observer.

This is a key consequence of Einstein’s theory of special relativity. Simultaneity is not absolute but depends on the observer’s state of motion.

It is the mass-weighted average position of all particles in the system. It can lie outside a physical object (e.g., a doughnut).

α = dω/dt, analogous to linear acceleration a = dv/dt.

This is the operational definition: a frame where an object with no net force acting on it moves with constant velocity (or remains at rest).

It does not exchange matter or energy with its surroundings.
Explanation: An isolated system has no interactions across its boundary, no transfer of mass, heat, or work.