Question

Suppose at the Talladega Superspeedway, Ryan Newman drives a racecar at a constant speed of 186 miles/hour around the track during qualifying. Newman’s car not undergone any acceleration because its speed was constant. True/False?

Answer 1

As we know that acceleration is the time derivative of velocity and not of speed.

Speed is scalar quantity which represent only magnitude not the direction. if the speed is constant ie remains same then direction may vary and this change in the direction causes the acceleration of the object.

An object doing circular motion having constant speed then it's direction changes at every point. If the direction changes then velocity also changes and hence it causes acceleration.

While accelerating the speed of the object may be constant.  

So,  The statement is not correct, because constant speed does not guarantee that velocity is also constant. In constant speed if car is moving then direction keep changing and this change in direction causes change in velocity and hence we can say that the acceleration also does not remain same.