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How can forces act?
By contact and at distance
What are the two effects that forces can produce on bodies?
Deformation
Change in the state of motion
What is the unit of force in the International System?
Newtons
How can we calculate the acceleration acquired by a body if we know the force that we apply and the mass of the body?
Using the formula F= m·a
How can we calculate the deformation of a spring if we know the force that we apply and the spring constant?
Using the formula K =F/Al
What is the total force applied to a body if we push it with 90 N and friction is 10 N?
80 N
15 N
What is the weight of a 2 kg body?
19,6 N
What is the mass of a body with a weight of 98 N?
10 kg
How do we call the statement that says that the force applied to a spring and its elongation are proportional?
Hooke's law
Why do you think that there is no gravity in the International Space Station?
Because of the big distance to the Earth
How is it call the attractive force that appears between bodies depending on their mass and their distance?
Gravity
How do we call the bodies that deform but do not regain their initian length when the force disappears?
Plastic bodies
How do we call bodies that do not deform (they break or fracture)?
Rigid bodies
Protons (+), neutrons (0), electrons (-)
Name two differences between gravity and electric force.
Gravity depends on the mass, electric force on the charge.
Gravity is always attractive. Electric force may be attractive or repulsive.
How do we call the force that makes compasses point North?
Magnetic force
10 m/s2
Calculate the spring constant of a spring if when we hang a body with a mass of 1 kg the lenght of it increases by 4.9 cm.
2 N/cm
What is the mass of a body if in a planet with a g=5 m/s2, its weight is 10 N?
2 kg
When do we say that a body has been deformed?
When a force is applied and its length varies along the force’s line of action.
Calculate friction if when we push a body with a mass of 2 kg with a force of 5 N, the acceleration produced is 1,5 m/s2.
2 N
Calculate g of a planet knowing that a body with a weight of 19,6 N on Earth has a weight on that planet of 16 N.
8 m/s2
Calculate the mass of a body knowing that hanging it on a spring with a k=8 N/cm, it elongates by 4 cm.
3.27 kg
Calculate the mass of a body if when we push it with 30 N it acquires an acceleration of 3 m/s2 (Friction =6 N).
8 kg