Question

1. john is pushing a 200 - kilogram sled, accelerating at 3.5 m/s². his friend jane joins in pushing the sled in the same direction, and sleds acceleration increases to 4.5 m/s². how much force is jane applying to the sled? 150 n 100 n 200 n 50 n

Explanation:

Step1: Use Newton's second - law

According to Newton's second - law $F = ma$, where $F$ is the net force, $m$ is the mass, and $a$ is the acceleration.

Step2: Calculate the net force before and after

The mass of the sled $m = 200$ kg. The acceleration before Jane joined is $a_1=3.5$ m/s², so the force applied by John is $F_1=ma_1 = 200\times3.5=700$ N. The acceleration after Jane joined is $a_2 = 4.5$ m/s², so the net force is $F_2=ma_2=200\times4.5 = 900$ N.

Step3: Find Jane's force

Let the force applied by Jane be $F_J$. Since $F_2=F_1 + F_J$, then $F_J=F_2 - F_1$. Substituting the values of $F_1$ and $F_2$, we get $F_J=900 - 700=200$ N.

Answer:

200 N