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Question 7
A race car traveling at 120 km/h accelerates at a rate of 0.8 m/s2 for 20 s. What is the final speed of the race car?
207.3 km/h
213.8 km/h
177.6 km/h
125.8 km/h

Respuesta :

semsee45

Answer:

177.6 km/h

Explanation:

[tex]\boxed{v=u+at}[/tex]

where:

  • u is initial velocity in meters per second (m/s).
  • v is final velocity in meters per second (m/s).
  • a is acceleration in meters per second per second (m/s²).
  • t is time in seconds (s).

Given values:

  • u = 120 km/h
  • a = 0.2 m/s²
  • t = 20 s

Convert the initial velocity from kilometers per hour to meters per second by dividing the value by 3.6:

[tex]\implies u=\dfrac{120}{3.6}=\dfrac{100}{3}\; \sf m/s[/tex]

Subsist the values of u, a and t into the formula and solve for v:

[tex]\begin{aligned} \textsf{Using} \quad v&=u+at\\\\\implies v&=\dfrac{100}{3}+0.8(20)\\\\&=\dfrac{148}{3}\; \sf m/s\end{aligned}[/tex]

Convert back to km/h by multiplying the value by 3.6:

[tex]\implies v=\dfrac{148}{3} \times 3.6=177.6\; \sf km/h[/tex]

Therefore, the final speed of the race car is 177.6 km/h.

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