Topic: Homework ?- on velocity and speed. Please help!?**Question:**
An object travels 3m East in 0.5 seconds and then goes 4m North in 1.5 seconds. What is the speed of the object? What is its velocity?
I have tried to re-read my notes, and textbook and I still dont get it.

June 24, 2019 / By Alivia

Speed is a scalar quantity that means it does NOT take into account the direction traveled. Speed is distance traveled over time Velocity is a vector quantity so it does take into account the direction of motion. Velocity is displacement over time. For example if you walk 10 meters forward then turn around and walk 5 meters back then the distance traveled is 15 meters. The displacement would be the distance of your final position from your initial position. Since you would be 5 meters from your start position your displacement is five meters. In your homework problem the distance traveled is 4m + 3m. this divided by the time is the speed The displacement is is found using the pythagorean theorem c² = a² + b² a = 4m b = 3m The square root of c² is the displacement. If you divide this by the time you will find the velocity.

👍 214 | 👎 3

Did you like the answer? Hi! This is quite a question, but hopefully I can help a little. In uniform circular motion (aka something moving in a perfect circle - which I assume this is what the question is getting at) speed only matters on distance and time. So the speed would be 440m/25s or 17.6 m/s (I think) for a complete lap. Half the lap would be 220m/25s = 8.8 m/s. Velocity is a vector however - Average velocity is the simple average of the initial velocity and the final velocity. So if the athlete only runs half a lap when he starts his velocity is "v" when he finishes on the other side his velocity is "-v". He starts out going east so his velocity in a westerly direction is "-v" and when he finishes its "v". So we get (Vi + Vf) / 2 = Average velocity. Input what we have: (-V + V) / 2 = 0 / 2 = 0 So his velocity when running half a lap is zero. If he completes one full lap his velocity is the same as where he started so we get: (V + V) / 2 = 2V / 2 = V So his velocity is whatever velocity he started with which is 17.6 m/s E You could also say that his velocity is tangential, but I think the previous explanation is answer you are looking for.

average speed (meters per second) is just going to be the total distance (meters) divided by the total time ( seconds) he went half way around the 440m circle in 25 seconds, so he went 220m in 25 sec, so his average speed was (220 / 25) mps part b is sneaky, since his direction was changing as he went around the circle. at the half way point, he is facing exactly the opposite direction as when he started. I suspect his average 'westerly velocity' is going to be zero, but you should think about that. and possibly the same for part c where his starting point matches his end point, so he has no change at all in his western position. His SPEED of course is only dependent on the actual distance he travels (the 440m) Good luck!

It travels 3 m east and 4 m north. It travels 7 meters in 2 seconds. So average speed is 7/2 m/s It travels 3 m east and 4 m north | | (4 meters) - - - (3 meters) Exact displacement is 5 meters. 3-4-5 triangle there ... So velocity is 5/2 m/s

👍 90 | 👎 -4

Speed of the object is the time rate of change of DISTANCE with respect to time. So add the distance and get total distance, add the time to get total time and divide speed = (3+4)/(.5+1.5) speed = 7/2=3.5 m/s Velocity of the object is the time rate of change of DISPLACEMENT with respect to time. Now displacement is the shortest distance from initial to final point. If you look at the question then you see the object first travels to the right and then upwards, and if we join the initial and final points it becomes a right angled triangle with the hypotenuse as the DISPLACEMENT. after solving the displacement comes out to be 5. velocity = displacement / time = 5/2=2.5 i hope it helps!

👍 88 | 👎 -11

The answer above is ok and technically correct, but there is an easier solution... Acceleration = (Final Velocity - Initial Velocity)/Time for Change so a = (v-u)/t a = (-35 - 45)/0.01 a = -80/0.01 a = -8*10^3 m/s^2 as required. Negative sign indicates it is towards the East since we made the initial velocity towards the West +ve Best wishes

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