Efficiency  =  
                 (useful work you get out of it) / (work you put into it)
           =        (100,000 J)  /  (250,000 J)  
           =            0.4  =  40%    (choice-A) 
        
             
        
        
        
The answer is true a convex lens can produce a real image but not a viral image
        
             
        
        
        
Answer:
 h = 9.83 cm
Explanation:
Let's analyze this interesting exercise a bit, let's start by comparing the density of the ball with that of water
        
let's reduce the magnitudes to the SI system
          r = 10 cm = 0.10 m
          m = 10 g = 0.010 kg
          A = 100 cm² = 0.01 m²
the definition of density is
           ρ = m / V
the volume of a sphere
          V =  
           V =  π 0.1³
 π 0.1³
           V = 4.189 10⁻³ m³
let's calculate the density of the ball
            ρ =  
            ρ = 2.387 kg / m³
the tabulated density of water is
          ρ_water = 997 kg / m³
we can see that the density of the body is less than the density of water. Consequently the body floats in the water, therefore the water level that rises corresponds to the submerged part of the body. Let's write the equilibrium equation
             B - W = 0
             B = W
              
where B is the thrust that is given by Archimedes' principle
            ρ_liquid  g V_submerged = m g
            V_submerged = m / ρ_liquid
we calculate
             V _submerged = 0.10 9.8 / 997
              V_submerged = 9.83 10⁻⁴ m³
The volume increassed of the water container
            V = A h
             h = V / A
let's calculate
             h = 9.83 10⁻⁴ / 0.01
             h = 0.0983  m
this is equal to h = 9.83 cm
 
        
             
        
        
        
Answer:
v = 0.059 m/s
Explanation:
To find the final speed of Olaf and the ball you use the conservation momentum law. The momentum of Olaf and the ball before catches the ball is the same of the momentum of Olaf and the ball after. Then, you have:
 (1)
  (1)
m: mass of the ball = 0.400kg
M: mass of Olaf = 75.0 kg
v1i: initial velocity of the ball = 11.3m/s
v2i: initial velocity of Olaf = 0m/s
v: final velocity of Olaf and the ball
You solve the equation (1) for v and replace the values of all variables:

Hence, after Olaf catches the ball, the velocity of Olaf and the ball is 0.059m/s
 
        
             
        
        
        
Answer:
Explanation:
a)
Firstly to calculate the total mass of the can before the metal was lowered we need to add the mass of the eureka can and the mass of the water in the can. We don't know the mass of the water but we can easily find if we know the volume of the can. In order to calculate the volume we would have to multiply the area of the cross section by the height. So we do the following.
100 x 10cm = 1000
 x 10cm = 1000
Now in order to find the mass that water has in this case we have to multiply the water's density by the volume, and so we get....
 x 1000
 x 1000 = 1000g or 1kg
 = 1000g or 1kg
Knowing this, we now can calculate the total mass of the can before the metal was lowered, by adding the mass of the water to the mass of the can. So we get....
1000g + 100g = 1100g or 1.1kg
b)
The volume of the water that over flowed will be equal to the volume of the metal piece (since when we add the metal piece, the metal piece will force out the same volume of water as itself, to understand this more deeply you can read the about "Archimedes principle"). Knowing this we just have to calculate the volume of the metal piece an that will be the answer. So this time in order to find volume we will have to divide the total mass of the metal piece by its density. So we get....
20g ÷  = 2.5
 = 2.5 
c)
Now to find out the total mass of the can after the metal piece was lowered we would have to add the mass of the can itself, mass of the water inside the can, and the mass of the metal piece. We know the mass of the can, and the metal piece but we don't know the mass of the water because when we lowered the metal piece some of the water overflowed, and as a result the mass of the water changed. So now we just have to find the mass of the water in the can keeping in mind the fact that 2.5 overflowed. So now we the same process as in number a) just with a few adjustments.
 overflowed. So now we the same process as in number a) just with a few adjustments.
 x (1000
 x (1000 - 2.5
 - 2.5 ) = 997.5g
) = 997.5g
So now that we know the mass of the water in the can after we added the metal piece we can add all the three masses together (the mass of the can. the mass of the water, and the mass of the metal piece) and get the answer.
100g + 997.5g + 20g = 1117.5g or 1.1175kg