a car starts from rest and accelerates uniformly to reach a speed of 21 m/s in 7.0s. What was the speed of the object after 2.0 seconds?
V = Vo + a*t.
21 = 0 + a*7, a = 3 m/s^2.
V = 0 + 3*2 = 6 m/s.
To find the speed of the object after 2.0 seconds, we can use the equation for uniform acceleration:
v = u + at
Where:
v = final velocity
u = initial velocity
a = acceleration
t = time
Given:
u = 0 m/s (car starts from rest)
v = 21 m/s (speed after 7.0 seconds)
t = 7.0 s
Let's calculate the acceleration first:
a = (v - u) / t
a = (21 m/s - 0 m/s) / 7.0 s
a = 21 m/s / 7.0 s
a = 3 m/s²
Now, we can find the speed after 2.0 seconds:
v = u + at
v = 0 m/s + 3 m/s² * 2.0 s
v = 0 m/s + 6 m/s
v = 6 m/s
Therefore, the speed of the object after 2.0 seconds is 6 m/s.
To find the speed of the car after 2.0 seconds, we can use the equations of uniformly accelerated motion.
The equation we need to use is:
v = u + at
where:
- v is the final velocity (which we want to find)
- u is the initial velocity (in this case, the car starts from rest, so u = 0)
- a is the acceleration
- t is the time
We know that the car accelerates uniformly, so the acceleration is constant. In this case, we can find the acceleration using another equation:
a = (v - u) / t
Given that the car's final velocity is 21 m/s and the time taken is 7.0 seconds, we can calculate the acceleration:
a = (21 - 0) / 7.0 = 3 m/s²
Now we can substitute the values we have into the first equation to find the speed of the car after 2.0 seconds:
v = u + at
v = 0 + (3 × 2.0)
v = 6 m/s
Therefore, the speed of the car after 2.0 seconds is 6 m/s.