PHY 101 Mock Test 1

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

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.

This is the definition of a perfectly elastic collision.

The boat’s velocity relative to the shore is the vector sum of its velocity across the river and the river’s velocity downstream. With both constant, the resultant is constant, leading to straight-line motion at an angle.

Impulse, J = ∫ F dt (or F_avg Δt for constant force), is a measure of the change in momentum it produces.

Mechanical energy is lost to heat and sound (non-conservative forces). However, when considering all forms of energy, the total energy of the universe (ball + Earth + surroundings) is conserved.

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

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.

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

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.

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

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

θ = ω₀ t + (1/2)αt²
Explanation: This is the rotational kinematic equation, analogous to s = u t + (1/2) a t² in linear motion.

A world line on a space-time plot shows an object’s position (space) at every moment (time).

The force on the bullet forward is paired with an equal and opposite force on the gun backward, causing recoil. It also illustrates conservation of momentum.

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.

Dimensionally: [ML⁻¹T⁻²] = [ML⁻³]ᵃ [LT⁻¹]ᵇ. Solving gives: For M: 1 = a; for L: -1 = -3a + b → b=2; for T: -2 = -b → b=2.

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

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

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.