Answer:
5.6s
Explanation:
Step1: Identify the given parameters
acceleration(a) = 4m/s²
initial velocity (u)= 0 (since the car started from rest)
final velocity (v) = 80km/hr
final velocity(v) in m/s = [tex]80\frac{(km)}{(hr)} X\frac{(1000m)}{(1km)} X\frac{(1 hr)}{(3600s)}[/tex]
= [tex]\frac{80,000(m)}{3,600(s)}[/tex]
=22.22m/s
Step2: calculate the time it takes the car to attain speed of 80km/hr = 22.22m/s
acceleration(a) = change in velocity per time
[tex]acceleration = \frac{(final velocity)-(initial velocity)}{time}[/tex]
[tex]a= \frac{v-u}{t}[/tex]
[tex]t=\frac{v-u}{a}[/tex]
[tex]t=\frac{22.22-0}{4} (s)[/tex]
a= 5.555 seconds
a≅5.6s
It takes 5.6 seconds to reach at s speed of 80 km/hr starting from rest.
Speed is defined as the rate of change of the distance or the height attained. it is a time-based quantity. it is denoted by u for the initial speed while u for the final speed. its si unit is m/sec.
The given data in the problem is;
a is the uniform acceleration= 4.0 m/s²,
v is the speed= 80 km/hr =22.22 m/sec
u is the initial speed=0 m/sec
The acceleration is defined as the rate of change of the velocity;
[tex]\rm a = \frac{v-u}{t} \\\\ \rm a = \frac{22.00-0}{4} \\\\ \rm a = 5.6 sec[/tex]
Hence it takes 5.6 seconds to reach at s speed of 80 km/hr starting from rest.
To learn more about the speed refer to the link;
https://brainly.com/question/7359669
