A car with a mass of 1.2 × 103 kilograms starts from rest and attains a speed of 20 meters/second in 5 seconds. What net force acted on the car to cause that acceleration?

Question

A.
3.0 × 102 newtons
B.
6.0 × 102 newtons
C.
1.2 × 103 newtons
D.
4.8 × 103 newtons
E.
1.2 × 104 newtons

Answer 1

To find the net force acting on the car, we first need to calculate its acceleration. We can use the formula for acceleration (\(a\)):

\[ a = \frac{\Delta v}{\Delta t} \]

Where:

• \(\Delta v\) is the change in velocity
• \(\Delta t\) is the change in time

In this case:

• The initial velocity (\(v_i\)) is 0 m/s (the car starts from rest)
• The final velocity (\(v_f\)) is 20 m/s
• The time interval (\(\Delta t\)) is 5 seconds

Now we can calculate the acceleration:

\[ a = \frac{20 , \text{m/s} - 0 , \text{m/s}}{5 , \text{s}} = \frac{20 , \text{m/s}}{5 , \text{s}} = 4 , \text{m/s}^2 \]

Next, we apply Newton's second law to find the net force (\(F\)):

\[ F = m \cdot a \]

Where:

• \(m\) is the mass of the car (1.2 × 10³ kg)
• \(a\) is the acceleration (4 m/s²)

Now we can calculate the force:

\[ F = (1.2 \times 10^3 , \text{kg}) \cdot (4 , \text{m/s}^2) = 4.8 \times 10^3 , \text{N} \]

Thus, the net force that acted on the car is:

\[ \boxed{4.8 \times 10^3 , \text{newtons}} \]

The correct answer is D. 4.8 × 10³ newtons.