Question

A car has a mass of 710 kg. It starts from rest and travels 40.0 m in 3.0s. The car is uniformly accelerated during the entire time. How big is the net force acting on the car?

Answer 1

`6300 "N"`

Explanation:

We will employ the following equation of kinematics

`x = 1/2at^2`

which describes an object traveling in one dimension with a constant acceleration and an initial velocity of zero.

We know the displacement and the time elapsed so we may solve for the acceleration:

`40.0 "m" = 1/2a(3.0"s")^2`

Solving for `a` yields:

`a = 8.89 "m"/"s"^2`

Now, knowing the acceleration of the car as well as the mass of the car we can apply Newton's second law, which states

`F_("net") = ma`

All we need to do is plug in our values for `m` and `a`:

`F_("net") = 710"kg"*8.89 "m"/"s"^2 = 6311.9 "N"`

Considering the fact that our final answer should have only two significant digits, we will round to the nearest hundred:

`F_("net") = 6300 "N"`