00:00imagine two cars moving at sixty kilometers per hour one reaches home safely the other crashes at a turn same speed so what went wrong
00:10the answer lies in three powerful words speed velocity and acceleration by the end of this video physics will finally make sense every movement around us walking running driving flying comes under one chapter of physics called motion
00:27first up speed speed tells us how fast an object is moving it does not care about direction only one question matters how much distance is covered in how much time the formula is simple speed equals distance divided by time
00:43so if you walk one hundred meters in fifty seconds your speed is two meters per second easy right now here's an important point whether you walk forward backward left or right if the distance and time are the same your speed remains the same
00:58this is because speed is a scalar quantity it has magnitude or a value but no direction now let's move on to velocity velocity is smarter than speed it tells us how fast an object is moving and in which direction
01:13its formula is velocity equals displacement divided by time displacement is just the straight line distance from your start point to your end point with a specific direction
01:24they have different velocities here's a classic example to really nail this concept
01:29your total distance covered is twenty meters so your speed is not zero but your displacement your final distance from the start is zero so your velocity is zero this is a huge difference
01:42velocity is a vector quantity it needs both magnitude and direction finally let's talk about acceleration the real power player
01:51most people think acceleration just means speeding up but that's not the whole story acceleration means any change in velocity the formula is acceleration equals the change in velocity divided by time let's look at some daily examples when a car starts from rest at a green light and speeds up it is accelerating
02:10its velocity is increasing when you apply the brakes and the car's speed decreases this is also acceleration specifically called negative acceleration or deceleration its velocity is decreasing but here's the part most students miss even if an object's speed stays constant if it changes direction it is accelerating think of a car moving in a circle at a steady thirty kilometers per hour
02:36its speed isn't changing but its direction but its direction is constantly changing which means its velocity is constantly changing therefore it is accelerating the key takeaway is this any change in speed direction or both means acceleration is present
02:51so let's put it all together so let's put it all together in a quick comparison speed measures how fast you cover a distance and it doesn't care about direction it's a scalar velocity measures how fast your position changes in a specific direction it's a vector and acceleration measures any change in that velocity whether it's a change in speed direction or both it's also a vector now why does this all matter in the real world remember our car crash example from the beginning
03:19seatbelts save lives because they manage acceleration they increase the time it takes for your body to slow down in a crash which drastically reduces the force on you smooth braking prevents accidents because it involves a small controlled acceleration sharp turns even at a constant speed involve high acceleration and can cause a car to lose control and crash
03:44understanding this isn't just for exams it's about understanding how the world around you works and how to stay safe so to summarize one last time speed tells us how fast velocity tells us how fast and where and acceleration tells us how that motion changes if you understand this you have truly conquered the heart of physics if physics just became a whole lot easier for you make sure to hit that like button share this video with
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04:16simple thanks for watching
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