Question
1. A student drives south at 80m/s for four minutes, then turns west and drives at 100m/s for five minutes, and finally travels northwest at 120m/s for three minute. For this twelve minutes trip, find (a)the total vector displacement, (b) the average speed, and (c) the average velocity.
Solution
4.1
(161 Votos)
Benedita
Mestre · Tutor por 5 anos
Resposta
To solve this problem, we need to break down the trip into its components and calculate each part separately.### (a) Total Vector Displacement1. **Southward Displacement:** - Speed = 80 m/s - Time = 4 minutes = 240 seconds - Displacement = Speed × Time =
south2. **Westward Displacement:** - Speed = 100 m/s - Time = 5 minutes = 300 seconds - Displacement = Speed × Time =
west3. **Northwestward Displacement:** - Speed = 120 m/s - Time = 3 minutes = 180 seconds - Displacement = Speed × Time =
northwest Since northwest is at a 45-degree angle, we can split this into north and west components: - North component = \(21600 \, \text{m} \times \cos(45^\circ) = 15273.6 \, \text{m}\) - West component = \(21600 \, \text{m} \times \sin(45^\circ) = 15273.6 \, \text{m}\)**Total Displacement Components:**- South-North Component:
- West Component:
**Resultant Displacement:**Using Pythagorean theorem:
The direction can be found using:
### (b) Average SpeedAverage speed is the total distance traveled divided by the total time.- Total distance =
- Total time = 12 minutes = 720 seconds
### (c) Average VelocityAverage velocity is the total displacement divided by the total time.
The direction is the same as the total vector displacement, approximately
south of west.