Question

1. a car advertisement states that a certain car can accelerate from rest to 70 km/h in 7 seconds. find the cars average acceleration. (a=vf - vi/t2 - t1)
2. a lizard accelerates from 2 m/s to 10 m/s in 4 seconds. what is the lizards average acceleration? (a=vf - vi/t2 - t1)
3. a runner covers the last straight stretch of a race in 4 s. during that time, he speeds up from 5 m/s to 9 m/s. what is the runners acceleration in this part of the race? (a=vf - vi/t2 - t1)

Explanation:

Question 3

Step1: Convert the final velocity unit

\(70\text{ km/h}=\frac{70\times1000}{3600}\text{ m/s}=\frac{175}{9}\text{ m/s}\), initial velocity \(V_i = 0\text{ m/s}\), \(T_2 - t_1=7\text{ s}\)

Step2: Calculate the average acceleration

\(A=\frac{V_f - V_i}{T_2 - t_1}=\frac{\frac{175}{9}-0}{7}=\frac{25}{9}\text{ m/s}^2\)

Question 4

Step1: Identify the values

\(V_f = 10\text{ m/s}\), \(V_i = 2\text{ m/s}\), \(T_2 - t_1 = 4\text{ s}\)

Step2: Calculate the average acceleration

\(A=\frac{V_f - V_i}{T_2 - t_1}=\frac{10 - 2}{4}=2\text{ m/s}^2\)

Question 5

Step1: Identify the values

\(V_f = 9\text{ m/s}\), \(V_i = 5\text{ m/s}\), \(T_2 - t_1 = 4\text{ s}\)

Step2: Calculate the average acceleration

\(A=\frac{V_f - V_i}{T_2 - t_1}=\frac{9 - 5}{4}=1\text{ m/s}^2\)

Answer:

\(\frac{25}{9}\text{ m/s}^2\)