Question

A car advertisement states that a certain car can accelerate from rest to 70 km/h in 7 seconds.
Find the car's average acceleration.​

Answer 1

Answer:

Given:-

• Speed{v} = 70 km/hr

• Time = 7 seconds

To Find:-

• Average acceleration

Solution:-

The acceleration of an object can be calculated based on the formula,

⇒ $a = \dfrac{v-u}{t}$

where,

• a = acceleration

• v = final velocity

• u = initial velocity

• t = time taken

Here,

$70 km/hr = \dfrac{70 \:km}{1 \: hr}$ × $\dfrac{1 \: hr}{3600\:s}$ × $\dfrac{1000m}{1 km}$

$= 19\dfrac{4}{9}m/s$

As given in the question

• u = 0 m/s

• v = $19\dfrac{4}{9}m/s$

• t = 7 s

So,

⇒ $a = \dfrac{19\dfrac{4}{9}m/s-0 m/s}{7sec}$

⇒ $2\dfrac{7}{9}m/s²$

Hence the average acceleration of car is

${\red{\boxed{=2\dfrac{7}{9}m/s²}}}$

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Answer 2

Answer:

Given:-

Speed{v} = 70 km/hr

Time = 7 seconds

To Find:-

Average acceleration

Solution:-

The acceleration of an object can be calculated based on the formula,

⇒  

where,

a = acceleration

v = final velocity

u = initial velocity

t = time taken

Here,

×  ×  

As given in the question

u = 0 m/s

v =  

t = 7 s

So,

⇒  

⇒  

Hence the average acceleration of car is

Explanation: