A car moving at a speed of approximately 176.5 km/h. 923 m in front of the car, there is a truck moving at a speed of 84.2 km/h in the same direction.

1.What is the name of the physical process that would occur if both vehicles kept moving at constant speed?
2. How long would it take until this process occurred?
3. What is the minimal deceleration needed for the car in order to avoid the
physical encounter with the truck?The truck keeps moving at constant speed.
4. If the mass of the car (including passengers, bags, etc.) is 1769 kg, what is the minimal work that needs to be done by the friction force of the car's brakes in order to avoid hitting the truck from behind?

1. The name of the physical process that would occur if both vehicles kept moving at a constant speed is relative motion or relative velocity.

2. To calculate the time it would take for the two vehicles to reach the point of physical encounter, we need to compare their relative speeds and distances. Since they are moving in the same direction, the relative speed between them is the difference between their speeds:

Relative speed = Speed of the car - Speed of the truck

Relative speed = 176.5 km/h - 84.2 km/h

Now, convert the relative speed into meters per second for consistency:

Relative speed = (176.5 km/h - 84.2 km/h) * (1000 m/km) * (1/3600 h/s)

To find the time it would take for the vehicles to reach the point of physical encounter, divide the distance between them by the relative speed:

Time = Distance / Relative speed

Time = 923 m / Relative speed

Substitute the calculated relative speed into the equation to find the time.

3. To find the minimum deceleration needed for the car to avoid a physical encounter with the truck, we need to find the maximum time available before the encounter. The maximum time available is the time calculated in the previous step.

To calculate the minimum deceleration, use the following formula:

Deceleration = Change in velocity / Time

Deceleration = (Final velocity - Initial velocity) / Time

Since the car needs to decelerate to zero velocity relative to the truck, the final velocity is zero. The initial velocity is the velocity of the car, which is given in the question as 176.5 km/h.

Substitute the values into the equation and calculate the deceleration.

4. In order to calculate the minimal work done by the friction force of the car's brakes to avoid hitting the truck from behind, we need to know the change in kinetic energy.

The change in kinetic energy is given by the equation:

Change in kinetic energy = 0.5 * Mass * (Final velocity^2 - Initial velocity^2)

Since the final velocity is zero, the change in kinetic energy simplifies to:

Change in kinetic energy = 0.5 * Mass * Initial velocity^2

Substitute the values into the equation and calculate the minimal work needed.

1. The name of the physical process that would occur if both vehicles kept moving at a constant speed is relative motion or relative velocity.

2. To calculate the time it would take until the process occurs, we need to determine the relative velocity between the car and the truck. The relative velocity is the difference between their velocities, considering the same direction.

Relative velocity = Velocity of car - Velocity of truck

Given:
Velocity of car = 176.5 km/h
Velocity of truck = 84.2 km/h

Converting both speeds to meters per second (m/s):
Velocity of car = (176.5 km/h) * (1000 m/km) / (3600 s/h) = 49.02 m/s
Velocity of truck = (84.2 km/h) * (1000 m/km) / (3600 s/h) = 23.39 m/s

Relative velocity = 49.02 m/s - 23.39 m/s = 25.63 m/s

To calculate the time, we can use the formula:
Time = Distance / Relative velocity

Given:
Distance = 923 m
Relative velocity = 25.63 m/s

Time = 923 m / 25.63 m/s ≈ 36.01 seconds

Therefore, it would take approximately 36.01 seconds until the process occurs.

3. To find the minimal deceleration needed for the car to avoid a physical encounter with the truck, we need to calculate the relative distance between them at the beginning of the deceleration process. This can be done using the formula:

Relative distance = Relative velocity * Time

Given:
Relative velocity = 25.63 m/s (calculated above)
Time = 36.01 seconds (calculated above)

Relative distance = 25.63 m/s * 36.01 s ≈ 922.94 m

Since the car needs to avoid a physical encounter, the relative distance should be greater than the distance between them. Therefore, the minimal deceleration required for the car to avoid the truck is not possible in this scenario.

4. To calculate the minimal work required to avoid hitting the truck from behind, we need to calculate the kinetic energy of the car before deceleration. The work done by the friction force will be equal to the change in kinetic energy.

Given:
Mass of the car (m) = 1769 kg
Initial velocity of the car (v_i) = 49.02 m/s (calculated above, as the velocity of the car)

The initial kinetic energy (KE_i) of the car can be calculated using the formula:
KE_i = 0.5 * m * v_i^2

KE_i = 0.5 * 1769 kg * (49.02 m/s)^2 ≈ 429907.07 Joules

Since the car wants to avoid a collision, it needs to come to a stop. Therefore, the final kinetic energy (KE_f) is zero.

The work done by the friction force (W) is equal to the change in kinetic energy:
W = KE_f - KE_i
W = 0 - 429907.07 J
W ≈ -429907.07 J

The negative sign implies that work needs to be done on the car (by the friction force) to avoid the collision. The magnitude of the work is approximately 429907.07 Joules.

Therefore, the minimal work that needs to be done by the friction force of the car's brakes to avoid hitting the truck from behind is approximately 429907.07 Joules.