Energy in gravity, springs and movement

• Natuurkunde
• Middelbare school
• havo
• Leerjaar 1

Energy

Potential- and kinetic energy (gravity- and spring energy)

Learn for the test

Read the module carefully, study this lessonup and practice the assignments in red

= learn by heart!

Section 1

Introduction to energy

Energy

Quantity Energy (E)

Unit   Joule (J)

Energy is converted from one form to another and is never lost.

Law of  conservation of energy

The total amount of energy stays the same, the energy can only be converted from one form to another.

Assignments

3 - 6

8

Answers

3) 450000 J 

4) 0,23 J

5) 9,8 J

6) 0,000123 J

Section 2

Potential energy

Potential energy

This energy is stored in an object or system.

It is a collective noun for energy forms such as spring- and gravitational energy. 

This energy is converted when a spring is released or when an object falls.

. 

Potential energy

Collective noun for:

• Spring energy
• Gravitational energy

Kinetic energy

This is movement energy. Every object that moves has kinetic energy. If you want to increase or decrease the speed of the object you will either have to put in energy or take away energy.

Spring energy

When an elastic object is pushed in or stretched out, it stores spring energy.

The amount of spring energy depends on:

- How far the material is pushed in or stretched out

- How stiff or flexible the material is

Gravitational energy

When an object is being lifted, energy is stored in the object. This is a consequence of the gravitational pull of the earth on the object.

The gravitational energy depends on:

- The mass of the object

- The height of the object

Gravitational energy

Like in assignment 12:

On top of the gymnastic equipment the ball has 200 Joules of gravitational energy. Halfway up the equipment, the ball also has half the gravitational energy: 100 Joules. 

. 

Assignments

12

Answers

12) On top of the gym equipment, the ball has 200 J compared to the ground. On the ground the ball has a gravitational energy of 0 J. The ball goes from 200 J to 0 J in 4 steps.  Every step the energy goes down with 50 Joules.

A: 200 – 50 = 150 J

B: 100 J

C: 50 J

D: 0 J

E: 0 J 

Section 4

Movement and speed

Distance traveled and time

The distance traveled is the difference between the place where the object started and where the object ended up in a certain time. The time passed is the time that the object needs to travel a certain distance.

Average speed

You can calculate the the average speed by dividing the distance traveled by the elapsed time. 

averagespeed=​time​​distance​​

Convert

Assignments

13 until 16

Answers

13) 100 / 3,6 = 27,78 m/s

14) 30 / 3,6 = 8,33 m/s

15) 340 x 3,6 = 1224 km/h

16) 2,5 x 3,6 = 9,0 km/h 

Section 5

Capturing movements

Practice assignments

Every image is taken 0,4 seconds apart. The ruler is 1 meter long.

Make a distance-time table from image A to G. 

Put the information in a distance-time diagram. Put the time on the x-axis. 

Assignments

24 t/m 26

Antwoorden

26) Het diagram van opdracht 22 heeft een rechte lijn. Dit betekent dat het voorwerp een constante snelheid heeft. Het diagram van opdracht 24 is een lijn waarvan de steilheid afneemt. Dit betekent dat de snelheid afneemt. De bal gaat steeds langzamer rollen. 

Section 7

Kinetic energy

Kinetic energy

Kinetic energy is also called energy of movement. 

You can calculate it with:

kinetic energy = 0.5 × mass × speed × speed

mass in kg

speed in m/s

Assignment

29

Antwoorden

29) bewegingsenergie = 0,5 x massa x snelheid x snelheid

massa = 62 kg, snelheid = 15 km/h = 15 / 3,6 = 4,167 m/s

bewegingsenergie = 0,5 x 62 x 4,167 x 4,167 = 538 J 

Antwoorden oefentoets H10

1) bewegingsenergie, warmte, chemische energie, elektrische energie, etc.

2) 36 dJ = 3,6 J of 36 x 10-1 J

3) 0,0888 hJ = 8,88 J of 0,0888 x 102 J

4)

5) Elektrische energie wordt omgezet in zwaarte energie in het water.

6) 1. Door rendementen in de pompen zal er ook energie omgezet worden in warmte.

     2. In de watertorens kan in verhouding weinig water opgeslagen worden en daardoor maar weinig energie. 

Antwoorden oefentoets

Antwoorden oefentoets

9. Snelheid = afgelegde weg / verstreken tijd. Uit het diagram kan de afgelegde weg en verstreken tijd afgelezen worden. afgelegde weg = 9,5 cm = 0,095 m verstreken tijd = 6 x 0,10 = 0,60 s. v = 0,095 / 0,60 = 0,158 m/s

10.  De zwaarte energie neemt met gelijke hoeveelheid af als de afname van de hoogte. De hoogte halveert dus de zwaarte energie halveert ook. De zwaarte energie = 6,0 J

11. Als de bal op de grond ligt dan is de hoogte 0 m en is de zwaarte energie ook 0 J.

12. De bewegingsenergie bereken je met de massa en de snelheid.

Snelheid = 28,8 km/h = 28,8 / 3,6 = 8,0 m/s

bewegingsenergie = 0,5 x massa x snelheid x snelheid

bewegingsenergie = 0,5 x 0,300 x 8,0 x 8,0 = 9,6 J