physics chapter 3

Question 1

what is mass

Answer 1

mass is a measure of the quantity of matter in an object at rest relative to the observer.

Question 2

what is weight

Answer 2

weight is the gravitational force on an object that has mass

Question 3

what is a gravitational field

Answer 3

a gravitational field is a region of space in which a mass exert a force of attraction on another mass

Question 4

what is gravitational field strength

Answer 4

gravitational field strength (g) is defined as the gravitational force acting on it

Question 5

what is the formula to calculate the gravitational field strength

Answer 5

g = weight in newtons / mass of an object in kg

Question 6

how are mass and weight related

Answer 6

from the equation g=w/m, thus the weight of gravitational force (w) acting on an object is directly proportional to its mass (m)

Question 7

what is the gravitational field strength in g near its surface on earth

Answer 7

9.8 N/ kg

Question 8

what is a common weighing instrument to measure weight

Answer 8

spring balance

Question 9

what is a common measuring instrument used to measure mass

Answer 9

top pan balance

Question 10

what are some of the differences of mass and weight

Answer 10

mass
- amount of matter
- scalar quantity
- commonly measured in grams or kilograms
- independent of the gravitational field strength
- measured with a top pan balance

weight
- gravitational force
- a vector quantity
- commonly measured in newtons
- dependent on the gravitational field strength
- measured with a spring balance

Question 11

what is density

Answer 11

the density of a substance is defined as its mass per unit volume

Question 12

how do we calculate density

Answer 12

p ( density) = (mass) m/ (volume )v

Question 13

which units are commonly used to measure density

Answer 13

kilograms per cubic metres and grams per cubic centimetre

Question 14

why does heavy steel ship float

Answer 14

a large ship is an object that is made up of more than one material. In addition to steel, it contains a large volume of air in various rooms and cabins. Therefore, we will have to consider the average density of the ship

Question 15

write the procedure and each step to find the density of a regular shaped solid

Answer 15

apparatus needed : rectangular wooden block, digital balance and ruler

procedure:
1. measure the length, height and width of one of the blocks. Multiply these to find the volume.
2. using the digital balance, find the mass of the block
3. calculate the density by dividing mass by volume

Question 16

write the procedure and each step to find the density of a liquid

Answer 16

apparatus needed: measuring cylinder, digital balance

procedure:
1. measure the mass of an empty measuring cylinder
2. fill the measuring cylinder with 100ml of water and measure the mass of the measuring cylinder with water
3. find the mass of the water by subtracting the mass of an empty measuring cylinder by the measuring cylinder filled with water
4. read the volume of the water and calculate the density of the water by mass/volume

Question 17

write the procedure and each step to find the density of an irregular shaped solid

Answer 17

apparatus needed: measuring cylinder, digital balance, irregular object, string, eureka can and beaker

procedure:
1. measure and record the mass of an irregular liquid
2. tie a piece of string around the object
3. place the eureka can on a block and place a beaker under the spout
4. fill the eureka can with water until water is coming out of the sprout. stop adding any more water and wait until it has stopped dripping from the spout
5. carefully remove the beaker and replace it with a measuring cylinder or a clean beaker
6. slowly lower the irregular shape into the eureka can until it is fully submerged
7. collect any of the water that comes out of the spout and record its volume
8. remember, the amount of water displaced is equal to the object’s volume
9. calculate the object’s density, by mass/volume

Question 18

how is mass related to density

Answer 18

mass is directly proportional to its density. if mass increases, density increases, and if mass decreases the density decreases

Question 19

what are the factors of sinking and floating

Answer 19

upthrust and density

Question 20

what are some of the conditions for an object to sink

Answer 20

• substances that have lower densities than the liquid will float
• substances that have a higher density than the liquid sink

Question 21

substances that float on liquid

Answer 21

has lower densities than the liquid

Question 22

substances that sink in a liquid

Answer 22

has higher densities than the liquid