Topic 2 - Mechanics

Question 1

What is a vector quantity?

Answer 1

A quantity that has both size and direction e.g. acceleration, force, displacement.

Question 2

What is a scalar quantity?

Answer 2

a quantity that has size only. e.g. volume, mass, temperature.

Question 3

What is terminal velocity?

Answer 3

When the net force acting on a free-falling object becomes zero, and it no longer accelerates.

Question 4

Newton’s 1st Law

Answer 4

An object at rest tends to stay at rest unless acted upon by an external unbalanced force. (or an object in motion tends to stay in motion)
/
If the net force acting on an object is zero, its velocity is unchanged

Question 5

Newton’s 2nd Law

Answer 5

If there is an unbalanced force, then the object will accelerate in that direction.

Question 6

Newton’s 3rd Law

Answer 6

Every action has an equal and opposite reaction
OR
If object A exerts a force on object B, then object B exerts an equal and opposite force on object A.

Question 7

Friction

Answer 7

Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.

Question 8

What is Work?

Answer 8

work is the energy transferred to or from an object via the application of force along a displacement.. (the product of force and displacement)

Question 9

Law of Conservation of Momentum

Answer 9

In a closed and isolated system, the total momentum of objects in the system before a collision is equal to the total momentum in the system after a collision.

Question 10

Elastic Collision

Answer 10

A collision in which there is no net loss of kinetic energy in the system as a result of the collision. Both momentum and kinetic energy are conserved.

Question 11

Inelastic Collision

Answer 11

A collision in which there is a loss of kinetic energy while the momentum is conserved. (occurs when 2 objects collide and do not bounce away from each other)

Question 12

How to find the distance travelled from a velocity-time graph?

Answer 12

The distance travelled is represented by the area under the graph.

Question 13

Formula for density

Answer 13

Mass/ Volume

Question 14

What are the 2 equations that describe Newton’s second law of motion?

Answer 14

F = ma 
F= change in momentum/ change in time

Question 15

“Air resistance is negligible…” means that?

Answer 15

There are no frictional forces.

Question 16

When air resistance is negligible what does this mean for the forces acting on an object in parabolic motion?

Answer 16

When there is no friction during parabolic motion, the only force acting on the object is the gravitational force.

Question 17

What does the equation Ep = (1/2) k (change in x)^2 show?

Answer 17

The equation shows us that the potential energy stored in a spring is proportional to the spring constant and to the square of the distance by which the spring has been compressed/

Question 18

If two objects are fired with the same initial velocity and air resistance is negligible, what is their motion like?

Answer 18

Their motion will be identical

Motion only depends on the initial velocity

Question 19

What happens to horizontal velocity when air resistance is negligible?

Answer 19

Horizontal velocity does not change.

Question 20

Equation for work done involving kinetic energy?

Answer 20

Work done = final kinetic energy - initial kinetic energy.

Question 21

What does the area under a force-time graph represent?

Answer 21

The change in momentum

Question 22

What does the area under a force-displacement/ force-length graph represent?

Answer 22

Energy or work done