Answer:
Object 2 has the larger drag coefficient
Explanation:
The drag force, D, is given by the equation:
Object 1 has twice the diameter of object 2.
If 
Area of object 2, 
Area of object 1:
Since all other parameters are still the same except the drag coefficient:
For object 1:
For object 2:
Since the drag force for the two objects are the same:
Obviously from the equation above, c₂ is larger than c₁, this means that object 2 has the larger drag coefficient
Answer:
Option D
Explanation:
The work done can be given by the mechanical energy used to do work, i.e., Kinetic energy and potential energy provided to do the work.
In all the cases, except option D, the energy provided to do the useful work is not zero and hence work done is not zero.
In option D, the box is being pulled with constant velocity, making the acceleration zero and thus Kinetic energy of the system is zero. Hence work done in this case is zero.
Answer:
C. Surface area
Explanation:
The rate of chemical reaction depends on various factors such as:
- concentration and pressure
- nature of reactants
- temperature
- surface area
- presence of catalyst, etc.
Effect of surface area of reactants: the rate of a chemical reaction can be increased by increasing the the area of contact of the reacting substances. This is especially important when one or more of the reactants are solids., because only the particles of the solid that are exposed are able to take part in the reaction at each instant of time. Therefore, the greater the surface area of the solid reactant particles the faster the reaction.
The surface area of solid reactants can be increased by grinding or pelletizing, thus allowing for a greater contact between the reacting particles,
The instance in which one of the solid reactants was treated in a coffee grinder before adding to the reaction container is one way of increasing the surface area of a reactant.
