I am reading the definitions of vector and scalar quantities.
Scalar quantity – quantity with magnitude only.
Vector – quantity with magnitude and direction.
After that we have some quantities to distinguish,
But i am confuse with some quantities
-
Why speed is scalar and acceleration is vector? I think both include movement.
-
Why force vector it has no direction i guess.
-
What is the difference between velocity and speed? Because one is vector other scalar.
Please explain in layman language.
Edit –
Let i want to explain this to someone who dont have knowledge of formulas.
Best Answer
Your definitions of scalars and vectors are fine.
In specific answer to your questions:
$$\text{speed} = \frac{\text{distance}}{\text{time}}$$
and
$$\text{velocity} = \frac{\text{displacement}}{\text{time}}$$
Where distance is
displacement is
$$\text{displacement} = \text{change in position} = \text{final position} - \text{initial position}$$
The direction is based on where the final position is with respect to the initial position.
(time is also a scalar)
(Reference for quotes about distance and displacement).
Due to velocity being calculated based on the vector displacement, velocity is also a vector (going in the same direction as the displacement). Similarly, acceleration is based on a change in velocity, so is a vector as velocity is a vector.
$$\text{acceleration} = \frac{\text{change in velocity}}{\text{time}}$$
in the direction of the velocity - if the acceleration is negative, the object is decelerating (slowing down) or accelerating in the opposite direction.
Similarly for question 2. Force is calculated using the vector acceleration:
$$\text{force} = \text{mass} \cdot \text{acceleration}$$
in the direction of the acceleration.