Distance, Displacement, Speed, Velocity and Acceleration

which statement(s) is/are correct about displacement and distance?

• Both of them are scalars

• Both of them are vectors

• Displacement has direction and magnitude but distance has magnitude only.

• Both of them have the same SI unit, metres.

which statement(s) is/are correct about speed and velocity?

• Both of them are scalars

• Both of them are vectors

• Velocity has direction and magnitude but speed has magnitude only.

• Both of them have the same SI unit, metres per second (m/s)

What is acceleration? What is its unit?

• Change of velocity per unit time. Its unit is m/s/s or m/s² or ms^-2

• Change of speed per unit time. Its unit is m/s/s or m/s² or ms^-2

• Change of speed per unit distance. Its unit is m/s/m or Hz

• Change of displacement per unit time. Its unit is m/s or ms^-1

When there is no change in velocity (travelling at constant velocity), the acceleration is...

• ... negative m/s².

• ...positive m/s².

• ...zero m/s².

• ...increasing m/s².

• ...decreasing m/s².

When there is a uniform positive change in velocity (travelling with uniformly increasing velocity), the acceleration is...

• ... negative constant m/s².

• ...positive constant m/s².

• ...zero m/s².

• ...increasing m/s².

• ...decreasing m/s².

When there is a uniform negative change in velocity (travelling with uniformly decreasing velocity), the acceleration is...

• ... negative constant m/s².

• ...positive constant m/s².

• ...zero m/s².

• ...increasing m/s².

• ...decreasing m/s².

Select example(s) of free fall motion? from the following

• sky-diver falling from a helicopter to the ground.

• a bird flying around in the sky.

• a space rocket launching from the ground to the moon.

• a paper airplane gliding a cross a classroom.

• a ball falling from a rooftop to a road surface.

At the start of a free fall, the body...

• ...accelerates and its velocity is increasing.

• ...decelerates and its velocity is decreasing.

• ...not accelerating and its velocity is constant.

• ...not accelerating and its velocity is zero.

ATTENTION: The next FOUR questions are about free falling body! It's about a parachutist. Click "Noted" below for free points!

• Noted

• I am confused. I want my mommy.

FIRSTLY, the velocity increases. Which statement is correct about increasing velocity for a free falling body?

• Increasing velocity: when the acceleration is positive because the air resistance is less than the body's weight.

  Resultant force is downward.

• Increasing velocity: when the acceleration is negative because the air resistance is greater than the body's weight.

  Resultant force is upward.

• Increasing velocity: when the acceleration is positive because the air resistance is less than the body's weight.

  Resultant force is upward.

• Increasing velocity: when the acceleration is negative because the air resistance is greater than the body's weight.

  Resultant force is downward.