Answer:
- a change in color
- the formation of a precipitate
- the formation of bubbles
Explanation:
In a chemical reaction, there is always a rearrangement of atoms within the molecules of reactants to form new products. Such a change is different from changes in the physical form of molecules, e.g. shape.
Thus, according to this criteria, only three options are correct in the given question. A change in color is definitely an indication of chemical reaction because the emission of light before and after cannot be changed unless molecules are rearranged to form a new chemical. Likewise, precipitates form when a reaction takes place between chemically dissolved molecules to form less or not dissolvable compounds. In the end, the configuration of bubbles also indicates that the reaction has taken place because new gases are being released.
On the other hand, change in shape is a physical change because the composition doesn't need to also been changed. An example is the ice formation from water. Same is the case with "change of clear liquid to cloudy" because the addition of non-reactive substances could change the nature of liquid to cloudy however the reaction doesn't need to have taken place.
Answer:
For the car to move with constant velocity the additional force required is 
Explanation:
From the question we are told that
The net force of the car is 
Generally the total force acting on the car is the net force plus the force due to gravity acting in direction of the car (Let denote it as 
)
So the total force acting on the car is mathematically represented as
Here this F representing the total force can be mathematically represented as
Now for constant velocity to be attained, the acceleration of the car will be zero
So at constant velocity
=> 
So
=> 
=>
A useful formula that gives the free-fall distance from rest in 'T' seconds:
D = (1/2 G) x (T²)
G = 9.81 m/s²
1/2 G = 4.905 m/s²
D (5 seconds) = (4.905 m/s²) x (5 sec)²
= (4.905 m/s²) x (25 sec²)
= 122.625 meters .
Since the tower-top is 100m above ground,
the depth of the well, to the top of the water,
accounts for the additional 22.625 meters.
My question is: How do you know exactly when the stone hit the water ?
You probably stood at the top of the well and listened for the
sound of the 'plop'. But it took some time after the stone hit
the water for the sound of the plop to come back up to you.
Well, can't you just subtract that time ? Yes, but you need
to know how much time to subtract. That depends on the
depth of the well ... which is exactly what you're trying to
determine, so you don't know it yet.
Oh well. That's a deep subject.
Answer:
3.75m on the left end
Explanation:
Given data
Tim's weight = 500N= 0.5kN
Tim's fathers weight= 500*2= 1000N= 1kN
Tim and the fathers weight = 500+1000= 1500N= 1.5kN
Tim's uncle weight= 1.5kN
Length of seesaw= 5m
let the distance Tim's uncle sits be x
We know that summation of clockwise moment equals the summation of anticlockwise moment
Taking moment about the center of the seesaw
1.5*2.5= 1*x
3.75= 1x
Divide boths sides by 1
x= 3.75/1
x= 3.75m
Hence Tim's uncle will sit 3.75m on the left end
