The force needed to the stop the car is -3.79 N.
Explanation:
The force required to stop the car should have equal magnitude as the force required to move the car but in opposite direction. This is in accordance with the Newton's third law of motion. Since, in the present problem, we know the kinetic energy and velocity of the moving car, we can determine the mass of the car from these two parameters.
So, here v = 30 m/s and k.E. = 3.6 × 10⁵ J, then mass will be
Now, we know that the work done by the brake to stop the car will be equal to the product of force to stop the car with the distance travelled by the car on applying the brake.Here it is said that the car travels 95 m after the brake has been applied. So with the help of work energy theorem,
Work done = Final kinetic energy - Initial kinetic energy
Work done = Force × Displacement
So, Force × Displacement = Final kinetic energy - Initial Kinetic energy.
Thus, the force needed to the stop the car is -3.79 N.
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.
Answer:
B. 22,22,23,23,22,22,23
Explanation:
The standard deviation is a measure of dispersion or variability of a data set. In order to determine the data set that has the smallest standard deviation, we shall investigate on the ranges of the data sets given. The range of a data set is simply the difference between the maximum and minimum values in a data set. A data set that has a smaller range also has a smaller standard deviation.
From the alternatives given, the data set given by alternative B has the smallest range and consequently the smallest standard deviation.
The maximum value is 23 while the minimum is 22. The range is 1.
Gravitational pull changes between each planet while its the "MASS" which doesnt change
