Question

1. an object has an average speed of 7.4 km/h. which of the following describes two ways you could increase the average speed of the object to 14.8 km/h? a. reduce the distance that the object travels by half, keeping the time constant, or keep the distance constant and double the time. b. double the distance that the object travels, keeping the time constant, or keep the distance constant and reduce the time by half. c. reduce the distance that the object travels to one - fourth, keep the time constant, or keep the distance constant and increase the time by fourfold. d. increase the distance by fourfold, keeping the time constant, or keep the distance constant and reduce the time by one - fourth.

Explanation:

Step1: Recall speed formula

The formula for average speed is $v = \frac{d}{t}$, where $v$ is speed, $d$ is distance, and $t$ is time.

Step2: Analyze first - way to double speed

If we want to double the speed from $v_1=\frac{d_1}{t_1}$ to $v_2 = 2v_1$, when $t$ is constant ($t_2=t_1$), then $v_2=\frac{d_2}{t_2}=\frac{d_2}{t_1}$ and $2v_1 = 2\frac{d_1}{t_1}=\frac{d_2}{t_1}$, so $d_2 = 2d_1$ (double the distance while keeping time constant).

Step3: Analyze second - way to double speed

If we keep the distance constant ($d_2=d_1$), then $v_2=\frac{d_2}{t_2}=\frac{d_1}{t_2}$ and $2v_1=2\frac{d_1}{t_1}=\frac{d_1}{t_2}$, so $t_2=\frac{1}{2}t_1$ (reduce the time by half while keeping distance constant).

Answer:

B. Double the distance that the object travels, keeping the time constant, or keep the distance constant and reduce the time by half.