A force of 20 N is acted on a body to move it to a distance of 2 meters in the direction of the force.Calculate the work done.
W= F X D= 20 X 2 = 40 J
Complete: ..................solution and....................solution are bad electric conductors.
Sugary solution, hydrogen chloride in benzene.
Give 3 examples of nonrenewable resources of energy.
Fuel, food, nuclear reactions.
GR: Sodium and potassium are kept under kerosene surface.
To protect them from reaction with atmospheric oxygen.
What are examples of inactive metals?
Gold, Silver, Platinum, Nickel.
Describe what happens during the heating of solid for a long time.
M. gain T.E, the speed increases, At M.P the I.F weaken, so the I.S increases more and they become more free and the solid melts into liquid
GR: Atom is electrically neutral.
No. Of + protons inside nucleus equals to No. of - electrons outside nucleus
G.R: Atoms of inactive elements don't take part in the chemical reaction.
The outermost energy level is completely filled with electrons (they are stable)
This element is:.................../ No. of protons:.............../ No of neutrons:....................
Bromine, 35, 45
Complete : ...................energy is stored in a stretched spring
mechanical (potential)
GR: Cooking pots are made up of aluminium.
Good heat conductor and has high melting point.
If a ball thrown vertically to reach 20 m height and its weight is 5 N. Calculate its P.E.
P.E = W X H = 5 X 20 = 100 J
What is the energy used and produced?
electric or chemical / thermal
GR: Metallic spare parts are covered with grease.
To protect them from rust and corrosion.
GR: A drop of ink spreads through water.
Because the molecules of ink are in a continuous state of motion in all directions among water molecules.
What is the name of this element? / Write its electronic configuration .
Potassium / K 2, L 8, M 8, N 1
GR: No change in the potential energy when the object moves horizontally.
Because the height doesn't change ( = zero), and the P.E is directly proportional to the height
Complete: ................energy is stored in a car battery.
Chemical
We can divided materials according to the hardness into 3 groups: 1.......,2.........,3........
Rubber,Metals, Coal
What happens to the K.E when: Increasing the speed of an object to the double and decreasing its mass to half.
K.E is doubled
Calculate the mass of an object, its kinetic energy equals 90 J, and its speed equals 6 m.sec.
5 Kg
GR: Water is not used for put out petrol fire.
The D. of petrol is less than water, so it floats on the water surface and the fire keep burning.
Complete: By increasing the height of an object. ...................increases, ..................decreases, .............remains constant.
P.E , K.E , M.E