Unit 1.3: Dynamics

Question 1

State Newton’s first law of motion

Answer 1

If the resultant force on an object is zero then the object will either remain stationary, or if it was already moving, then it will continue to move with uniform motion.

Question 2

State Newton’s second law of motion

Answer 2

the rate of change of momentum is directly proportional to the applied (resultant) force and occurs in the same direction as the force

Question 3

State Newton’s third law of motion

Answer 3

If body A exerts a force ob body B, then body B will exert an equal and opposite force on body A

Question 4

State the equation associated with Newton’s second law of motion

Answer 4

F=ma where m is a constant

Question 5

Derive F=ma

Answer 5

Momentum=mass x velocity
F=Δmv/Δt
F=m x (v-u/t)
V-u/t=a
F=ma

Question 6

What is momentum?

Answer 6

Momentum is the product of force and velocity p=mv

Question 7

State the principle of conservation of momentum

Answer 7

“The total momentum of a system of interacting bodies will remain constant if
there are no external forces acting”.

Question 8

Is momentum a scalar or a vector

Answer 8

Vector-remember to state its direction

Question 9

What is an elastic collison

Answer 9

no kinetic energy is lost.

Question 10

What is an inelastic collision

Answer 10

where some of the kinetic
energy of the ‘system’ is lost to the surroundings.

Question 11

What is the gradient equal to on a momentum-time graph?

Answer 11

Force

Question 12

By looking at examples of N3rd law on objects, the situation or diagram can get very complicated. How would we make this simpler?

Answer 12

By drawing a free-body diagram

Question 13

What is a free-body diagram?

Answer 13

Free body diagrams separate the objects and drawing the forces on independently. Grouping the horizontal and vertical components together.