Acceleration and constant speed question

[dbzsongoku]

Can someone tell me which of the these is true or false and possibly explain it to me?

a)The acceleration of a car is zero when it is turning right at a constant speed
b)The acceleration of a car is zero when it is driving up a long straight incline at constant speed
c)The acceleration of a car is zero when it is topping the crest of a hill at constant speed
d)The acceleration of a car is zero when it is bottoming out at the lowest point of a valley at constant speed
e) The acceleration of a car is zero when it is speeding up as it descends a long straight decline.

Any help would be great.

thanks

 

[dextercioby]

What are your answers/hunches and the reasoning behind them...??

Daniel.

P.S.Read the "sticky" at the top of the thread...

 

[DB]

These are fairly easy questions if you just Think. Consider acceleration as the rate of change in speed, in your case ou can even think of it as a change in speed. Think of forces dependent on inclinations.

 

[christinono]

Make sure you know exactly what acceleration is. In order for an object to accelerate, its velocity must be changing.

 

[dextercioby]

THE VELOCITY VECTOR MUST BE CHANGING WITH TIME AS TO HAVE A NONZERO ACCELERATION VECTOR...

Daniel.

 

[dbzsongoku]

Is this correct?
a) false because direction is changing
b) true
c) true
d) true
e) false because magnitude of the accerlation is changing

 

[dextercioby]

The way i see it,only B is true...

Daniel.

 

[da_willem]

Is this correct?
a) false because direction is changing
b) true
c) true
d) true
e) false because magnitude of the accerlation is changing

why does your argment for a not apply to c and d?

 

[HallsofIvy]

These are fairly easy questions if you just Think. Consider acceleration as the rate of change in speed, in your case ou can even think of it as a change in speed. Think of forces dependent on inclinations.

Unfortunately, thinking THAT way will lead you to the wrong answer to at least one of these. Think "velocity" not "speed"!