Question

A car has a speed of 70 [mi/h]. When the brakes are applied only one force acts on the car. After this force is applied, the speed of the car is 20 [mi/h].

Answer 1

There is no actual question, so I am assuming you are asking for the deceleration.

Step-by-step explanation:

The change in speed of the car, given the application of the brakes, allows us to calculate the deceleration (negative acceleration) using the formula:

a= Δt / Δv

where:

a is the acceleration (or deceleration in this case),

Δv is the change in velocity (final velocity - initial velocity), and

Δt is the time it takes for this change to occur.

Let's use the given information:

Initial velocity ( v(i) ) = 70 mi/h

Final velocity ( v(f) ) = 20 mi/h

a= (20mi/h − 70mi/h) / Δt

Simplifying:

a= (−50mi/h) / Δt

We do not have the time (Δt) in the given information, so we cannot determine the exact deceleration without that information. If you have the time during which the deceleration occurred, you can plug it into the formula to find the acceleration.

Answer 2

The subject of this question is Physics, and it involves calculating the force acting on a car when its brakes are applied and the resulting change in speed.

Step-by-step explanation:

The subject of this question is Physics. The question pertains to the forces acting on a car when its brakes are applied and the resulting change in speed.

To solve this problem, we can use the equation:

Force = Mass x Acceleration

Given that the initial speed of the car is 70 mph and the final speed is 20 mph, we can calculate the change in velocity:

Change in Velocity = Final Velocity - Initial Velocity

Substituting the values, we have:

Change in Velocity = 20 mph - 70 mph = -50 mph

Since acceleration is the rate at which velocity changes, we can divide the change in velocity by the time taken to achieve this change:

Acceleration = Change in Velocity / Time

Without the time given, we cannot calculate the exact value of acceleration. However, based on the given information, we can conclude that a force was applied to the car to decelerate it, resulting in a decrease in speed.