Given : A car starts from rest and accelerates at a constant rate. After the car has gone 50 m it has a speed of 21m/s. What is the acceleration of the car?
Solution : As per the question, initial velocity is 0 m/s and final velocity is 21 m/s. Distance travelled is 50 m and we need to get the acceleration of the car.
We need to use the third equation of motion. Second equation is invalid as time is given in the formula but as per the data third equation is more comfortable.
★ 3ʳᵈ eq. of motion : v² - u² = 2aS ★
Putting all the given values according to the formula we get
Henceforth, acceleration is 4.41 m/s²
