A horse canters away from its trainer in a straight line, moving 50 m away in 9.4 s. It then turns abruptly and gallops halfway back in 1.7 s.
Part A
Calculate its average speed for the entire trip
Average Speed Calculation
Step 1: Determine the Total Distance Traveled
First Segment (Moving Away):
- Distance: 50 m
Second Segment (Galloping Back Halfway):
- Distance: 50 m / 2 = 25 m
Total Distance:
Total Distance = 50 m + 25 m = 75 m
Step 2: Determine the Total Time Taken
First Segment Time: 9.4 s
Second Segment Time: 1.7 s
Total Time:
Total Time = 9.4 s + 1.7 s = 11.1 s
Step 3: Calculate the Average Speed
Average Speed = Total Distance / Total Time
Average Speed = 75 m / 11.1 s ≈ 6.76 m/s
Physics Problem - Part B
A horse canters away from its trainer in a straight line, moving 50 m away in 9.4 s. It then turns abruptly and gallops halfway back in 1.7 s.
Part B
Calculate its average velocity for the entire trip, using "away from the trainer" as the positive direction.
Express your answer using two significant figures.
Remember that average velocity is a vector quantity that depends on the total displacement and total time.
Average Velocity Calculation
Note: Using "away from trainer" as positive direction
Step 1: Determine Displacement
Displacement is the straight-line distance from start to finish with direction.
First Segment (Moving Away - Positive):
- Displacement: +50 m
Second Segment (Returning - Negative):
- Displacement: -25 m (halfway back)
Total Displacement:
Total Displacement = +50 m + (-25 m) = +25 m
Step 2: Determine Total Time
First Segment Time: 9.4 s
Second Segment Time: 1.7 s
Total Time:
Total Time = 9.4 s + 1.7 s = 11.1 s
Step 3: Calculate Average Velocity
Average Velocity = Total Displacement / Total Time
Average Velocity = 25 m / 11.1 s ≈ 2.252 m/s
Rounded to two significant figures: 2.3 m/s
Key Difference from Average Speed
While average speed (6.76 m/s) considers total distance traveled (75 m),
average velocity only considers the net displacement (25 m) from the starting point.
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