Chapter 5: Preparing for the test

• Natuurkunde
• Middelbare school
• havo, vwo
• Leerjaar 3

Preparing for the test

Preparing the test

Hi,

I had some technical issues at home with my video software which I could not solve in time. So, no video but instead a lessonUp with a voice over!

I will go over the main definitions and principles of this chapter once more. I hope you will find it helpfull. 

Do not forget to practice yourselves.

 

Whenever an object is at rest or moving at constant speed in a straight line (constant velocity), Newton’s 1st Law of motion must come to your mind.

Concepts on Newton’s 1st Law are: Net force = resultant force = 0N, a = 0m/s2 , all forces are balanced.

If the object is accelerating or decelerating, that means the forces are unbalanced. Newton’s 2nd Law of Motion must come to your mind.

Concepts on Newton’s 2nd Law are: There is net force or resultant force, unbalanced forces, there is acceleration or deceleration.

Misconception

SIMULATION

A

B

C

D

E

A

B

C

D

E

a = +

a = 0

a = -

a = -

a = +

At what time does B overtake A ?

Surface:

(16 x 10) + 16 x (ΔT) =

160 + 16 ΔT

Surface:

1/2 x (20 x 10) + 20 x (ΔT) =

100 + 20 ΔT

100 + 20 ΔT = 160 + 16 ΔT 

20 ΔT - 16 ΔT = 160 - 100 

4 ΔT = 60

ΔT = 15 s

t = 10 + 15 s = 25 s

Proof that it is correct:

100 + 20 ΔT = 100 + 20 x 15 = 400 m

160 + 16 ΔT = 160 + 16 x 15 = 400 m

surfaces should be equal

ΔT

ΔT

The velocity-time graph of an object moving in a straight line is shown. If the average velocity is 20 m.s-1. The acceleration [m.s-2] from A to B is

answer

What length of time corresponds to the
distance between
X and Y on the tape?

1. 0,10 s
2. 0,11 s
3. 0,17 s
4. 0,18 s

At what speed was the tape moving between X and Y?

1. 2,5 cm/s
2. 5 cm/s
3. 50 cm/s
4. 100 cm/s

In the figure the distance moved by a trolly in successive seconds is given by the spacing between the dots

1. 2 cm/s
2. 3 cm/s
3. 4 cm/s
4. 6 cm/s