Physics, 30.08.2019 08:30 log40

Acar is traveling at a constant velocity of 60 km/h for 4 hours. choose the correct statement about the acceleration of the car. a) the acceleration of this car is zero. b) the acceleration of this car is positive. c) the acceleration of this car is negative. d) the acceleration of this car is 15 m s .

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The best we can say about this question is that it's ambiguous ...
we can't be sure that it gives us enough information to answer it.

You start by saying that the car's velocity is constant. But then you
seemingly illustrate that by telling us only its speed, and nothing about
the direction it's driving.

'Velocity' means its speed AND direction. (You and I need to tell Mr. Plz
below that he should focus more attention on learning his definitions.)

If velocity is constant, then speed AND DIRECTION are constant.
'Acceleration' means ANY change in speed OR direction. That's right !
Going around a curve at constant speed is accelerated motion.

We know that the car in the question never changes its speed for 4 hours.

If its DIRECTION never changes during the same time, then there has been
no acceleration.

If it ever changes direction ... turns a corner or goes around a curve in the
road ... then there has been acceleration, during the time its direction was
changing.

Answer from: Quest

Ais the

Answer from: Quest

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

$f\alpha \frac{dp}{dt}$

⇒ $f= k \frac{dp}{dt}$

here k is the proportionality constant whose value is 1.

$f=\frac{dp}{dt}$

$f= \frac{d[mv]}{dt}$

$f= m\frac{dv}{dt} +v\frac{dm}{dt}$

$f=ma+v\frac{dm}{dt}$ [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.

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