ACTIVITY 1
Complete the following chart:
MASS WEIGHT
5 g ?
? 30 N
3.2 kg ?
? 100 N
ACTIVITY 2
Tell if the following affirmations are true or false.
A. You weigh the same wherever you are.
B. Two objects with the same mass, weigh always the same.
C. You have the same mass wherever you are.
D. Your father has a lot of force.
E. The SI unit of force is the kilogram (kg).
WORKSHEET 1
Exercise 1
What happens if you hit or push a ball in these cases?
a) The ball is at rest.
b) The ball is in motion.
c) The ball is at rest and in contact to a wall.
▪ Exercise 2
What are the effects of a force (what changes when a force is acting on an object)?
▪ Exercise 3
What types of forces are there?
▪ Exercise 4
Set two examples of non-contact forces (forces at a distance).
▪ Exercise 5
What type of force is exerted?
a) If you drop an object from a height.
b) If you drop an object from a height and you give it an impulse downwards.
c) If a girl pushes a table.
d) If a mule drags a cart.
▪ Exercise 6
Read the text and afterwards answer the questions.
Probably, you have ever moulded figures out of plasticine or bread crumbles. The force of your fingers changes little by little the shape of the matter until you get the figure you wish. If you stretch an elastic band or a spring you can increases its size. The bigger the force you apply, the longer the band. Forces can deform matter, however, some bodies, for example, rocks, cannot be deformed.
The deformable bodies (springs, plasticine, elastic bands) can be either plastic objects or elastic objects. What is the difference? The plastic bodies do not recover their original shape when the force is no longer there, but the elastic bodies recover their original shape.
On the other hand, the bodies that cannot be deformed are called rigid bodies and they break or burst if the force applied on them is big enough.
a) What causes the deformation of solid bodies?
b) What material would you use to make a model figure: plastic or elastic? Explain why.
c) Give two examples of plastic objects and two examples of elastic objects
d) What does non-deformable mean?
▪ Exercise 7
Work out the weight of a woman on The Earth, on The Moon and on Mars if his mass is 60 kg. (Look up
the value of gravity on the Internet)
▪ Exercise 8
What is the difference between mass and weight?
▪ Exercise 9
What would be the mass of an object that weighs 1 N on Earth?
▪ Exercise 10
A Martian has a weight of 925 N on Mars.(g=3,7 m/s²)
a) What would be his mass if he travelled to The Earth?
b) What would be his weight?
c) Would he be happy living in the Earth? Why
ACTIVITY 3
Calculate the net (resultant) force, the direction and orientation of these cases, if you know that the big arrow represents 20 N and the smallest 12 N. No other forces are taken into account.
ACTIVITY 4
First draw a scheme about these problems. Calculate the net (resultant) force of a case in which two people is pulling an object. No other forces are taken into account
Case A.
First person to the right with 4 N
Second person pulling down with 8 N
Case B.-
First person to the right with 4 N
Second person with the same direction and the opposite orientation with 8 N
Case C
First person to the right with 4 N
Second person is pulling with 8 N, same direction and orientation.
NON COMPULSORY ACTIVITIES JUST TO REVIEW
Click on it and look for physics, choose forces and interaction. On the right, it appears a menu, choose mass and weight or contact or non contact forces. There are some activities that you can do with the answers
