Question

a spring scale shows a net force of 0.8 n acting on a 1.5 - kg mass. what happens to the acceleration of the object if the net force is decreased to 0.4 n? (1 point)
the acceleration increases to 2 times its original value, or about 2.13 m/s².
the acceleration increases to four times its original value, or about 0.13 m/s².
the acceleration decreases to a quarter of its original value, or about 0.13 m/s².
the acceleration decreases to half of its original value, or about.26 m/s².

Explanation:

Step1: Calculate initial acceleration

According to Newton's second - law $F = ma$, so $a_1=\frac{F_1}{m}$. Given $F_1 = 0.8\ N$ and $m = 1.5\ kg$, then $a_1=\frac{0.8}{1.5}\ m/s^2\approx0.53\ m/s^2$.

Step2: Calculate final acceleration

When $F_2 = 0.4\ N$ and $m = 1.5\ kg$, using $a=\frac{F}{m}$ again, we have $a_2=\frac{0.4}{1.5}\ m/s^2\approx0.26\ m/s^2$.

Step3: Analyze the change in acceleration

We find the ratio $\frac{a_2}{a_1}=\frac{\frac{0.4}{1.5}}{\frac{0.8}{1.5}}=\frac{0.4}{0.8}=\frac{1}{2}$. So the acceleration decreases to half of its original value.

Answer:

The acceleration decreases to half of its original value, or about 0.26 m/s².