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 four times its original value, or about 0.13 m/s².
the acceleration increases to 2 times its original value, or about 2.13 m/s².
the acceleration decreases to half of its original value, or about.26 m/s².
the acceleration decreases to a quarter of its original value, or about 0.13 m/s².

Explanation:

Step1: Calculate initial acceleration

Use 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 $a=\frac{F}{m}$, we have $a_2=\frac{0.4}{1.5}\ m/s^2\approx0.26\ m/s^2$.

Step3: Analyze the change in acceleration

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 $0.26\ m/s^2$.