Physics · Motion In A Plane · NEET
Speed is a scalar. It tells you only how fast an object moves, for example 60 km/h, with no direction. Velocity is the vector version: it is 60 km/h toward north. So speed = magnitude of velocity, and velocity = speed + direction. NEET often uses this pair to trick you, so read the word carefully.
Mass just tells you how much matter is in a body (5 kg), and 5 kg does not point anywhere, so it is a scalar. Force pushes or pulls in a specific direction (20 N downward, 20 N to the right), so you must state the direction; that makes it a vector. Two 5 N forces give 10 N only if they point the same way, but 0 N if they are opposite.
Yes. A scalar can be positive, negative, or zero, but the minus sign only means 'less than a reference', not a direction. Temperature -10 C, charge -2 C, and potential energy -3 J are all scalars. The minus in a vector like -5 m means direction reversed, which is different.
Correct. Distance is the total path length you travel (always positive, a scalar). Displacement is the straight-line change in position from start to end with a direction (a vector). Walk 3 m east then 3 m west: distance = 6 m, but displacement = 0. This is a very common NEET distinction.
No. Scalars add by simple arithmetic: 3 kg + 2 kg = 5 kg. Vectors add by direction. Two vectors of 3 and 4 units give 7 only if they are parallel, 1 if opposite, and 5 if perpendicular (using 3-4-5). This is why 8 N and 6 N perpendicular forces give 10 N, not 14 N.
The magnitude and direction of the acceleration produced in a body of mass 5 kg when two mutually perpendicular forces 8 N and 6 N act on it are respectively:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
A scalar is a quantity with only magnitude (a number and a unit), such as mass, time, speed, and temperature. A vector is a quantity with both magnitude and direction, such as velocity, force, displacement, and acceleration.
Scalars: mass, distance, speed, temperature, energy (or time, work, charge). Vectors: displacement, velocity, acceleration, force, momentum (or weight, electric field).
Electric current is a scalar, even though it has a direction of flow. It is a scalar because it does not follow the vector law of addition (currents at a junction add by simple arithmetic, as in Kirchhoff's rule), and it has no true directional character in space.
Pressure is a scalar. Although force has direction, pressure is force per unit area acting equally in all directions at a point in a fluid, so it has only magnitude. NEET sometimes tests this because students expect it to be a vector.
Because it decides how you add quantities. Scalars add by arithmetic, but vectors add by the triangle or parallelogram law and depend on the angle between them. Mixing these up gives wrong answers in projectile, force, and relative-velocity problems.
