Question

a runner runs 400 meters north in 50 seconds. what is the speed of the runner? a car travels at 3 km in 3 hours. what is the speed of the car? a tornado approaches. the wind velocity was 8 m/s going north. if the winds velocity increased to 23 m/s in 3 seconds going north, what is the winds acceleration? a roller coaster starts at rest and reaches a velocity of 20 m/s in 5 seconds. what is the acceleration of the roller coaster? at what time interval was the object at rest?

Explanation:

2.3

Step1: Recall speed formula

Speed = Distance / Time

Step2: Identify values

Distance = 400 m, Time = 50 s

Step3: Calculate speed

Speed = $\frac{400}{50}=8$ m/s

Step1: Recall acceleration formula

Acceleration = $\frac{\Delta v}{\Delta t}$

Step2: Identify initial and final velocity and time

Initial velocity $v_0 = 8$ m/s, final velocity $v = 23$ m/s, time $\Delta t=3$ s

Step3: Calculate acceleration

Acceleration = $\frac{23 - 8}{3}=\frac{15}{3}=5$ m/s²

Step1: Recall acceleration formula

Acceleration $a=\frac{v - v_0}{t}$, where $v_0 = 0$ (starts from rest), $v = 20$ m/s, $t = 5$ s

Step2: Calculate acceleration

$a=\frac{20 - 0}{5}=4$ m/s²

Answer:

8 m/s

2.4