Answer:
 
Let d be the density of fluid.
So , Initial reading of balance, F1 =30dg N
After the level reaches 50cm^3
 
Final reading of balance , F2 =50dg N
Given that difference between final and initial reading is 30g
i.e, F2 −F1
 
 =30 g
⟹50dg−30dg=30g
⟹20dg=30g
⟹d=30g/20g
 
 
⟹d=1.5g/cm^3
 
So, density of fluid is 1.5g/cm^3
 
        
             
        
        
        
If an airplane is flying at 300 km/h to the east and is facing a headwind of 18.0 km/h, the final velocity can be calculated using simple vector addition. In this case, the planes velocity is positive (+330 km/h) and head wind has a negative component (-18.0 km/h). Vector addition yields +330 km / h + (-18.0 km /h) = 312 km / h. 
        
             
        
        
        
Two atoms of the same element can have different numbers of protons
false
diff nos neutrons ... isotopes,
diff protons ... diff elements
 
        
             
        
        
        
Answer:
1.8*10^8m/s
Explanation:
Using
L= lo√1-v²/c²
So making v subject we have
V= c√1-4.8²/6²
V= 0.6*c
V= 0.6*3E8m/s
V= 1.8*10^8m/s
 
        
             
        
        
        
There will not be enough momentum from the first hill to cross another hill if he same or larger size because of the way potential energy and kinetic energy works it will not be able go as high as it could go on he fist hill.