Answer:
Weight is used most often for measuring solid whereas volume is used most often for measuring liquid.
Explanation:
Weight is used most often for measuring solid, because solids have definite shape. Weight is usually expressed in Newton (N) because it is a function of mass and gravity. ( weight = mass x gravity).
Whereas volume is used most often for measuring liquid, usually expressed in cubic meter (m³) because liquids have no definite shape, rather they occupy the volume of their container.
Answer:
Explanation:
Given
Each student exert a force of 
Let mass of car be m
there are 18 students who lifts the car
Total force by 18 students 
therefore weight of car 
mass of car 

(b)
When balanced forces follow up on an object, the object won't move. If you push against a wall, the wall pushes back with an equal but opposite force. Neither you nor the wall will move. Forces that cause a change in the motion of an object are unbalanced forces.
I'll tell you how I look at this, although I may be missing something important.
Position = x(t) = 0.5 sin(pt + p/3)
Speed = position' = x'(t) = 0.5 p cos(pt + p/3)
Acceleration = speed' = position ' ' = x ' '(t) = -0.5 p² sin(pt + p/3)
At (t = 1.0),
x ' '(t) = -0.5 p² sin( 4/3 p )
In order to evaluate this, don't I still have to know what 'p' is ? ?
I don't think it can be evaluated with the information given in the question.
Explanation:
Calculating this according to the m/s rate
Now solving the question
If the car goes 20 m/s mathematically we can generate it as
15 × 60 = 600 secs
If the car goes 20 meters per every second it means
The car will go 20 meters for 900 secs
Which is 900 ×20 = 18000m/s
=18000÷1000 = 1km
Therefore the answer is 18km