Question

Please help and show working please

Answer 1

We have to build a schema of all the forces applied to the car:

We have air resistance and friction, both against the direction of motion.

We have gravity (due to the downhill angle) and motor force, acting in the direction of motion.

So, we can set up the equation

$F=ma$

where F is the sum of all forces:

$F_m+F_g-F_f-F_{ar}=ma$

Where $F_m$ is the motor force, $F_g$ is the gravity force, $F_f$ is the friction force, and $F_{ar}$ is the air resistance force (note that the signs depend on whether the force is along or against the direction of motion.

We can solve for $F_m$ as follows:

$F_m = ma-F_g+F_f+F_{ar}$

We know everything, except for $F_g$. The formula for the force parallel to the direction of motion in a sloped plane with angle $\theta$ is

$F_\parallel = F\sin(\theta)$

So, we can substitute:

$F_m = 4321\cdot 0.3-4321\sin(10)+1500+3000\approx 5045.966 \approx 5046$