A rocket is launched vertically from rest with a constant thrust until the rocket reaches an altitude of 25 m and the thrust ends. The rocket has mass 2 kg and thrust force 35 N. Neglecting air resistance, determine (a) the speed of the rocket when the thrust ends, (b) the maximum height reached by the rocket, and (c) the speed of the rocket when it returns to the ground.
a) Let's calculate the work done by the rocket until the thrust ends.
But we know the work is equal to change of kinetic energy, so:
b) Here we have a free fall motion, because there is not external forces acting, that is way we can use the free-fall equations.
At the maximum height the velocity is 0, so v(f) = 0.
c) Here we can evaluate the motion equation between the rocket at 25 m from the ground and the instant before the rocket touch the ground.
Using the same equation of part b)
The minus sign of 25 means the zero of the reference system is at the pint when the thrust ends.
Young students show a preference for which modality?
Answer. In the present study, it was found that 61% students had multimodal learning style preferences and that only 39% students had unimodal preferences. Amongst the multimodal learning styles, the most preferred mode was bimodal, followed by trimodal and quadrimodal respectively
Be a qt today lolololololol
thank you for the free points
The cost of hiring new employees outpaces the raises for established employees is A. Salary compression
B. Occupational based pay
C. Merit pay
D. Need for Achievement
do you have to make the right decisions to be a person who has been a member who is not the first time a great person who has a job in a day of his life or
In a home, air infiltrates from the outside through cracks around doors and windows. Consider a residence where the total length of cracks is 62 m and the total internal volume is 210 m3 . Due to the wind, 9.4 x 10-5 kg/s of air enters per meter of crack and exits up a chimney. Assume air temperature is the same inside and out and air density is constant at 1.186 kg/m3 . If windows and doors are not opened or closed, estimate the time required for one complete air change in the building.
Time period = 41654.08 s
Internal volume is 210 m^3
Rate of air infiltration
length of cracks 62 m
air density = 1.186 kg/m^3
Total rate of air infiltration
total volume of air infiltration
A chemical process converts molten iron (III) oxide into molten iron and carbon dioxide by using a reducing agent of carbon monoxide. The process allows 10.08 kg of iron to be produced from every 16.00 kg of iron (III) oxide in an excess of carbon monoxide. Calculate the percentage yield of iron produced in this process.
percentage yield = 63%
The yield efficiency or percentage yield measure the amount of products that are formed from a given amount of reactant. For a percentage yield of 100, all the reactants are completely converted to product. Mathematically, the percentage yield is given by:
If 100 J of heat is added to a system so that the final temperature of the system is 400 K, what is the change in entropy of the system? a)- 0.25 J/K b)- 2.5 J/K c)- 1 J/K d)- 4 J/K
Given data in given question
heat (Q) = 100 J
temperature (T) = 400 K
to find out
the change in entropy of the given system
we use the entropy change equation here i.e
ΔS = ΔQ / T ...................a
Now we put the value of heat (Q) and Temperature (T) in equation a
ΔS is the entropy change, Q is heat and T is the temperature,