10TH GRADE · KINEMATICS

Speed and uniform movement

Path, time, speed, average speed and addition of movements.

18 minutes12 theory cards

LESSON MATERIAL

Basic Concepts

Mechanical movement

Changes in the position of a body relative to other bodies over time.

Movement is always described relative to a selected reference body: the passenger is at rest relative to the carriage, but moves relative to the platform.

Uniform movement

A movement in which equal distances are covered in equal periods of time.

With such movement, the speed does not change, so the path can be found by simply multiplying the speed and time.

Speed addition

The rule for determining the speed of a body relative to one system by its velocities relative to other systems.

The velocities are added as vectors, taking into account the direction. This is how one moves from motion within the reference system to the motion of the system itself.

LESSON MATERIAL

Physical quantities

Speed

v

The speed of changing body position.

Unit: meter per second · $\frac{\mathrm{m}}{\mathrm{s}}$

Average speed

v_{\text{sr}}

The ratio of the entire path to the entire travel time.

Unit: meter per second · $\frac{\mathrm{m}}{\mathrm{s}}$

First folding speed

v_1

The speed of one movement involved in the addition of speeds.

Unit: meter per second · $\frac{\mathrm{m}}{\mathrm{s}}$

Second folding speed

v_2

The speed of the second movement involved in the addition of speeds.

Unit: meter per second · $\frac{\mathrm{m}}{\mathrm{s}}$

LESSON MATERIAL

Lesson formulas

Uniform speed

v=\frac{S}{t}

Speed equals distance divided by time.

Average speed

v_{\text{sr}}=\frac{S}{t}

The average speed is equal to the entire path divided by the entire time.

Meters per second and kilometers per hour

1\,\frac{\mathrm{m}}{\mathrm{s}}=3{,}6\,\frac{\mathrm{km}}{\mathrm{ch}}

One meter per second is equal to three point six kilometers per hour.

Speed addition

\vec{v}=\vec{v_1}+\vec{v_2}

The resulting speed is equal to the vector sum of the component speeds.

Paths over successive intervals

l_1:l_2:l_3:\ldots=1:3:5:7:\ldots

When starting from rest and constantly accelerating, the distances at equal successive intervals are treated as odd numbers.

Condition: The body begins to move from rest, the acceleration is constant, the time intervals are equal.

Related formulas

Speedv · m/s

PRACTICE

Tasks on the topic

Kinematics10 class · 32 problems