# How can momentary speed exist

## Understanding Physics 2, Student Book

11 11.4 A laser pistol used against traffic offenders Speed ​​limit Current speed Average speed 11.5 A GPS navigation device also determines the speed. 11.6 An anemometer to determine the wind speed 4. How do we calculate the average speed? With roughly the same movement, you can determine the speed of a body, for example, as follows: a) Measure the distance that the body covers in meters. b) Measure the time in seconds that the body needs for this path. c) Divide the distance (in m) by the time (in s). The toy speed (Fig.11.1) E1 Let a wind-up toy vehicle or crawling doll drive or run one meter over the table and stop the time. For example, if the car needs 5 seconds for 1m, do the math: 1m: 5 s = 0.2 m __ s. The car has a speed of 0.2 m __ s (= 0.2 ∙ 3.6 km __ h = 0.72 km __ h). 5. What types of movement are there? A car gets faster and faster in the first few seconds after starting - they say: “The car accelerates.” The distances covered become longer in the individual seconds. That means the speed is increasing. When the car brakes, the speed decreases with every following second. The acceleration a is, for example, the change in speed v per time: a = v: t. Every change in a movement is called acceleration in physics. If the vehicle drives at a constant speed, it is a uniform movement. The Glöckerlbahn (Fig.11.3) E1 Fasten hanging bells on a wooden channel (approx. 1.5–2 m long) evenly spaced (eg 20 cm) and at a height of approx. 2–3 cm. Let a wooden ball (diameter approx. 3 cm) roll down the inclined channel. The time between the ringing bells gets shorter and shorter - the ball accelerates. Now change the position of the bells so that the time intervals sound the same. Infobox: v for engl. velocity ... speed; s for engl. space… space; t for engl. time… time V2 11.1 The toy speed formula for calculating the average speed: Speed ​​= distance: time v = s: t M v increases. v becomes smaller. v remains the same. 1 2 3 0s 1 2 3 1s 2s 3s 4s 5s 6s 7s 8s Distance s Time t become faster - G raf becomes steeper Graf becomes steeper uniform - Graf remains equally slower - Graf becomes flatter 11.2 Accelerated (1, 3) and uniform (2) Movements V3 11.3 The Glöckerlbahn With a steady movement the speed remains the same. Acceleration is the change in the movement of a body, for example when it becomes faster or slower. M worksheets t9z7gm For testing purposes only - property of the publisher öbv