Magnitude of Force Required to Slow Down the Car

To calculate the magnitude of force required to slow down the car, we can use Newton's second law of motion, which states that the force acting on an object is equal to the mass of the object multiplied by its acceleration.

Given:
Mass of the car, m = 1200 kg
Initial velocity, u = 90 km/hr = 25 m/s
Final velocity, v = 18 km/hr = 5 m/s
Time taken, t = 4 seconds

Step 1: Convert the velocities from km/hr to m/s
The initial velocity in m/s can be calculated by multiplying the given velocity in km/hr by (5/18).
Initial velocity, u = 90 km/hr * (5/18) = 25 m/s

The final velocity in m/s can be calculated in the same way.
Final velocity, v = 18 km/hr * (5/18) = 5 m/s

Step 2: Calculate the acceleration
The acceleration of the car can be calculated using the formula:
Acceleration, a = (v - u) / t

Substituting the given values,
Acceleration, a = (5 m/s - 25 m/s) / 4 s = -5 m/s²

Note: The negative sign indicates that the car is decelerating or slowing down.

Step 3: Calculate the magnitude of force
Using Newton's second law, we can find the magnitude of force required to slow down the car.
Force, F = m * a

Substituting the given values,
Force, F = 1200 kg * (-5 m/s²) = -6000 N

The magnitude of force required to slow down the car is 6000 N.

Summary:
- Given the mass of the car, initial velocity, final velocity, and time taken, we have calculated the magnitude of force required to slow down the car.
- To do this, we converted the velocities from km/hr to m/s, calculated the acceleration using the formula (v - u) / t, and then used Newton's second law (F = m * a) to find the magnitude of force.
- The magnitude of force required is determined to be 6000 N.
- It is important to note that the negative sign indicates that the car is decelerating or slowing down.