Physics — Semester A Practice

Question 1 of 10

TEKS 1A-4CEasy Word

The SI unit of electric current is:

AWatt

BVolt

CCoulomb

DAmpere

Explanation

📌 The ampere (A) is the SI unit of current. 1 A = 1 C/s. The other units name different quantities: the coulomb is charge, the volt is potential, and the watt is power.

Question 2 of 10

TEKS 1A-4CEasy Word

A student measures the mass of a sample as 0.00284 kg. Which expression correctly represents this mass in scientific notation with proper SI units?

A2.84 × 10³ kg

B2.84 × 10⁻³ kg

C28.4 × 10⁻⁴ kg

D2.84 × 10⁻² g

Explanation

📌 Move decimal 3 places right: 0.00284 → 2.84 × 10⁻³. Coefficient must satisfy 1 ≤ a < 10, and SI mass unit is kg. Common wrong answers come from has wrong exponent sign, violates scientific notation convention, and uses wrong unit (2.84 × 10⁻² g = 0.0000284 kg, two orders off).

Question 3 of 10

TEKS 1A-4CEasy Word

What is the SI unit of energy?

APascal (Pa)

BNewton (N)

CJoule (J)

DWatt (W)

Explanation

📌 The joule (J) is the SI unit of energy, defined as 1 N·m. Common wrong answers come from force, power (J/s), and pressure (N/m²).

Question 4 of 10

TEKS 5A-5EEasy Word

A cyclist travels 240 m in 30 s at constant velocity. What is her average velocity?

A7,200 m/s

B0.125 m/s

C8.0 m

D8.0 m/s

Explanation

📌 Average velocity v = d/t = 240 m / 30 s = 8.0 m/s. Common wrong answers come from multiplying (÷/× swap), taking reciprocal, and forgetting velocity units (m instead of m/s).

Question 5 of 10

TEKS 7D-7EEasy Word

A 3.0-kg object moves at a velocity of 5.0 m/s. What is its momentum?

A8.0 kg·m/s

B15 kg·m/s

C0.6 kg·m/s

D45 kg·m/s

Explanation

📌 p = mv = 3.0 × 5.0 = 15 kg·m/s. Common wrong answers come from dividing (÷ instead of ×), adding, and using wrong formula.

Question 6 of 10

TEKS 5F-5HEasy Word Diagram

According to Newton’s law of universal gravitation, if the distance between two objects is doubled while their masses remain the same, the gravitational force between them becomes:

Adoubled

Bfour times the original

Chalved

Done-fourth of the original

Explanation

📌 F = GmM/d². Force is inversely proportional to d². Double d → d² becomes 4d² → F becomes F/4. Common wrong answers come from treats it as direct proportion, applies 1/d instead of 1/d² (forgot the square), and squares wrong direction (direct instead of inverse).

Question 7 of 10

TEKS 5A-5EEasy Calc Word

Which quantity is a scalar?

Aspeed

Bvelocity

Cdisplacement

Dacceleration

Explanation

📌 Speed = magnitude of velocity, no direction → scalar. Velocity, displacement, and acceleration are vectors (have direction).

Question 8 of 10

TEKS 7A-7CEasy Calc Word Diagram

A person pushes a box with a horizontal force of 50 N over a distance of 8.0 m. If the person applies the force parallel to the direction of motion, how much work is done on the box?

A3,200 J

B400 J

C6.25 J

D42 J

Explanation

📌 W = F·d·cos θ, where θ = 0° for parallel force (cos 0 = 1). W = 50 × 8.0 × 1 = 400 J. Common wrong answers come from dividing (÷ instead of ×), subtracting, and multiplying one extra time.

Question 9 of 10

TEKS 5F-5HMedium Calc Word Diagram

A 4.0-kg block slides down a frictionless ramp inclined at 30° to the horizontal. What is the magnitude of the block’s acceleration along the ramp? Use g = 9.8 m/s².

A9.8 m/s²

B4.9 m/s²

C8.5 m/s²

D2.0 m/s²

Explanation

📌 On a frictionless incline, acceleration along the ramp = g·sin θ = 9.8 × sin(30°) = 9.8 × 0.5 = 4.9 m/s². Mass cancels — same rate for any object at same angle. Common wrong answers come from unnecessarily divided by mass, using cos(30°) instead of sin(30°) — the sin/cos swap, and using full g without decomposition.

Question 10 of 10

TEKS 5F-5HMedium Calc Word Diagram

A 5.0-kg block on a horizontal surface is pushed with a horizontal applied force of 30 N. A frictional force of 12 N opposes motion. What is the block’s acceleration?

A3.6 m/s²

B8.4 m/s²

C6.0 m/s²

D2.4 m/s²

Explanation

📌 Net force = 30 − 12 = 18 N right. a = F_net/m = 18/5.0 = 3.6 m/s². Common wrong answers come from ignoring applied force, ignoring friction, and adding forces instead of subtracting (sign error — friction opposes motion).

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