Math  /  Algebra

QuestionA car accelerates from rest at 4.4 m/s24.4 \mathrm{~m} / \mathrm{s}^{2}. How much time does it need to attain a speed of 5 m/s5 \mathrm{~m} / \mathrm{s} ?
Answer in units of s. Answer in units of s.

Studdy Solution

STEP 1

What is this asking? How long does it take a car starting from a standstill to reach a speed of 5 m/s5 \mathrm{~m} / \mathrm{s} if it's accelerating at 4.4 m/s24.4 \mathrm{~m} / \mathrm{s}^{2}? Watch out! Don't mix up speed and acceleration; acceleration is how quickly the speed changes!
Also, remember that the car starts from rest, meaning its initial speed is 0 m/s0 \mathrm{~m} / \mathrm{s}.

STEP 2

1. Define Acceleration
2. Calculate the Time

STEP 3

Alright, so we know the car is accelerating at 4.4 m/s24.4 \mathrm{~m} / \mathrm{s}^{2}.
But what does that *really* mean?
It means that every second, the car's speed increases by 4.4 m/s4.4 \mathrm{~m} / \mathrm{s}.
That's our **rate of change**!

STEP 4

We can write this mathematically using the formula for acceleration: Acceleration=Change in SpeedChange in Time\text{Acceleration} = \frac{\text{Change in Speed}}{\text{Change in Time}}

STEP 5

Let's use variables to make things easier.
Let aa represent acceleration, vfv_f represent the **final speed**, viv_i represent the **initial speed**, and tt represent the time.
So, we have: a=vfvita = \frac{v_f - v_i}{t}

STEP 6

We're trying to find the time tt, so let's **rearrange the formula** to solve for it.
We can do this by multiplying both sides of the equation by tt and then dividing both sides by aa: ta=vfvittt \cdot a = \frac{v_f - v_i}{t} \cdot t ta=vfvit \cdot a = v_f - v_itaa=vfvia\frac{t \cdot a}{a} = \frac{v_f - v_i}{a}t=vfviat = \frac{v_f - v_i}{a}

STEP 7

Now we can **plug in the values** we know.
The **final speed** vfv_f is 5 m/s5 \mathrm{~m} / \mathrm{s}, the **initial speed** viv_i is 0 m/s0 \mathrm{~m} / \mathrm{s} (because the car starts from rest!), and the acceleration aa is 4.4 m/s24.4 \mathrm{~m} / \mathrm{s}^{2}. t=5 m/s0 m/s4.4 m/s2t = \frac{5 \mathrm{~m} / \mathrm{s} - 0 \mathrm{~m} / \mathrm{s}}{4.4 \mathrm{~m} / \mathrm{s}^{2}}

STEP 8

Let's **crunch the numbers**: t=5 m/s4.4 m/s2t = \frac{5 \mathrm{~m} / \mathrm{s}}{4.4 \mathrm{~m} / \mathrm{s}^{2}} t1.136 st \approx 1.136 \mathrm{~s}

STEP 9

So, it takes approximately 1.1361.136 seconds for the car to reach a speed of 5 m/s5 \mathrm{~m} / \mathrm{s}.

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