Physics of motion?

Question

In another round of shopping, Afshin is looking for a new hat. He walks 10 m at a rate of 2.0 m/s and then another 15 m at 1.5 m/s. Calculate the average speed for the entire walk?

can u pls show me the steps..

Answer 1

To find the average speed find the total distances traveled and divide that by the total time.

Therefore the answer is 25 /15 = 1.67m/s.

Another way is finding the sum of all the speeds for a particular equal distance and divide it by the number of speeds counted.

For the first 5m the speed is 2m/s
For the second 5m the speed is 2m/s.
For the third 5m the speed is 1.5 m/s
For the fourth 5m the speed is 1.5m/s.
For the fifth 5m the speed is 1.5 m/s

Sum of the speeds is (2 +2+1.5 + 1.5 +1.5) = 8.5.

Number of speeds is 5.

Average speed is 8.5/5 =1.7.


If we calculate the speed for each meter,
then for the first 10 meters we have 10 x2 = 20 for 10 such meters, and for the remaining 15 meters we have
15 x 1.5 = 22.5 for 15 meters.

Sum of the speeds is 42.5 for 25 numbers.

Average speed is 42.5 / 25 = 1.7 m/s

But the simplest way is to find the total distance and divide it by total time.

If the speed is uniformly varying then the average speed is found by adding the initial and final speed and dividing it by 2.

Answer 2

rand's method is right but messed up the arithmetic. Time is 5+10=15.

So average speed is
total distance/total time = 25 m/15s = 1.7 m/s

Answer 3

Average speed = total distance / total time

t=d/v

first walk takes: t=10/2=5.0s

second walk takes: t=15/1.5=10s

total time = 5.0+10.0 = 15.0s

total distance = 10+15 = 25m

Average speed = Total d / total t = 25/15 = 1.666 = 1.7m/s

Learn your formulas and definitions!!!!

Physics is Phun

Answer 4

Time taken first instance
2m/sec for 10 m = 10/2 = 5 seconds
Time taken second instance
1.5m/sec for 15 m = 15/1.5 = 10 seconds.
Total distance covered = 10m + 15m = 25 m
Total time = 5 sec + 10 sec = 25 sec
25 m covered in 25 sec = 25/25 = 1 m/sec
QED

Answer 5

1.66m/sec