Question

a car travels 20km/hr for 1.5h, 30km/hr for 2.0h, and at 40km/hr for 0.75 h. The car's average velocity is?

Answer 1

Answer on Question #53731, Physics Mechanics Kinematics Dynamics

a car travels 20km/hr for 1.5h, 30km/hr for 2.0h, and at 40km/hr for 0.75 h. The car's average velocity is?

Solution

The car's average velocity is given by Eq.(1)

$$v _ {a} = \frac {s _ {\text {total}}}{t _ {\text {total}}} = \frac {v _ {1} t _ {1} + v _ {2} t _ {2} + v _ {3} t _ {3}}{t _ {1} + t _ {2} + t _ {3}} = \frac {2 0 (km / hr) \cdot 1 . 5 hr + 3 0 (km / hr) \cdot 2 . 0 hr + 4 0 (km / hr) \cdot 0 . 7 5 hr}{1 . 5 hr + 2 . 0 hr + 0 . 7 5 hr} = 2 8. 2 4 km / hr$$

where $v_{1} = 20(km / hr)$ ; $v_{2} = 30(km / hr)$ ; $v_{3} = 40(km / hr)$ ; $t_{1} = 1.5hr$ ; $t_{2} = 2.0hr$ ; $t_{3} = 0.75hr$

Answer: $v_{a} = \frac{v_{1}t_{1} + v_{2}t_{2} + v_{3}t_{3}}{t_{1} + t_{2} + t_{3}} = 28.24km / hr$

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