It is given that by using track and cart we can record the time and the distance travelled and also the speed of the cart can be recorded. With all this data we can solve questions on the laws of motion.  
Like using the first law of motion we can determine the force of gravity acting on the cart that has moved a certain distance and the velocity or the speed of card has already been registered and since time is known putting the values in formula would help us calculate the gravitational pull acting on cart.
 
        
                    
             
        
        
        
Answer:0.27
Explanation:
Given
One worker Pushes with force 
other Pulls it with a rope of rope 
mass of crate 
both forces are horizontal and crate slides with a constant speed 
Both forces are in the same direction so Friction will oppose the forces and will be equal in magnitude of sum of two forces because crate is moving with constant speed i.e. net force is zero on it 

where  is the friction force
 is the friction force



where  is the coefficient of static friction
is the coefficient of static friction



 
        
             
        
        
        
Answer:
497.00977 N
3742514.97005
Explanation:
 = Density of water = 1000 kg/m³
 = Density of water = 1000 kg/m³
C = Drag coefficient = 0.09
v = Velocity of dolphin = 7.5 m/s
r = Radius of bottlenose dolphin = 0.5/2 = 0.25 m
A = Area
Drag force

The drag force on the dolphin's nose is 497.00977 N
at 20°C
 = Dynamic viscosity =
 = Dynamic viscosity = 
Reynold's Number

The Reynolds number is 3742514.97005
 
        
             
        
        
        
-Slow down 
-Speed up 
-Turning
Hope this helps