The brakes on your automobile are capable of creating a deceleration of 4.9 m/s2. if you are going 149 km/h and suddenly see a state trooper, what is the minimum time in which you can get your car under the 100 km/h speed limit?

You need at least 2.8 s to slow down your car to 100 km/h. If we add reaction time (≅0.3 s), you will need 3.1 s.

Explanation:

Hi there!

The equation of velocity for an object moving in a straight line is the following:

v = v0 + a · t

Where:

v = velocity at time t.

v0 = initial velocity.

a = acceleration.

t = time.

We have to find the time at which the velocity is 100 km/h with a decceleration of 4.9 m/s² and an initial velocity of 149 km/h. Let´s first convert km/h into m/s:

149 km/h · (1000 m / 1 km) · ( 1 h / 3600 s) = 41.4 m/s

100 km/h · (1000 m / 1 km) · ( 1 h / 3600 s) = 27.8 m/s

Now, let´s solve the equation of velocity for the time:

v = v0 + a · t

(v - v0) / a = t

Replacing with the data:

(27.8 m/s - 41.4 m/s) / -4.9 m/s² = t

Notice that the acceleration is negative because you are slowing down.

t = 2.8 s

You need at least 2.8 s to slow down your car to 100 km/h. If we add reaction time (≅0.3 s), you will need 3.1 s.

a longitudinal wave moves energy that is to the direction of the wave’s movement. - true

increasing transnational kinetic energy. because the transnational kinetic energy formula consists of only two variables, mass and velocity, increasing one of those properties is the only way to increase an object's transnational kinetic energy. increases to mass and velocity, however, do not have the same impact.