## Mathhelp346 3 years ago PLEASE HELP: An automobile accelerates at 1.77 m/s^2 over 6.00s to reach the freeway speed at the end of an entrance ramp. If the car's final speed is 88.0 km/h, what was its initial speed when it began accelerating? Express your answer in kilometers per hour.

1. micahwood50

$a = \frac{\Delta v}{t} = \frac{v_f - v_o}{t}$

2. micahwood50

Use this formula.

3. Mathhelp346

i know the formula im just having trouble converting the units

4. micahwood50

Alright, let convert 88 km/h to m/s. $\frac{ 88 \text{km} }{ \text{h} }\cdot\frac{ 1000 \text{m}}{ \text{km} }\cdot\frac{ 1 \text{h} }{ 3600\text{s} } = ?$

5. micahwood50

|dw:1349065649701:dw|

6. micahwood50

Does this clear everything?

7. Mathhelp346

24.4

8. Mathhelp346

yea

9. micahwood50

Yeah, now find Vo Then convert it back to km/h

10. Mathhelp346

so is it 13.78?

11. Mathhelp346

km/h

12. micahwood50

13.78 Is it in m/s ?

13. Mathhelp346

oops yes

14. Mathhelp346

how would i convert it back

15. micahwood50

Let me show you. |dw:1349067937197:dw|

16. micahwood50

|dw:1349068014177:dw|

17. micahwood50

$\frac{13.78 \cdot 3600 \text{km}}{1000 \text{h}}$

18. micahwood50

Just treat units as "variable." You know what I mean?

19. Mathhelp346

ok

20. Mathhelp346

so it would be 49.6 km/h

21. micahwood50

That's correct.

22. Mathhelp346

ok ty