Question

a stone is thrown vertically upward with the velocity of 25 metre per second. how long does it take to rich the maximum hight ?also calculate the hight

​

Answer 1

Answer:

Using the formulas to solve the problem is good, but let’s try and solve it directly with our intuition. Notice that maximum height is reached when the velocity becomes zero. So, vfinal=0

It is given that the initial velocity, vinitial=25m/s. The acceleration due to gravity is g=9.8m/s2 .This means that the velocity decreases by 9.8 m/s every second . Thus the velocity becomes zero at time, Δt=vinitialg=259.8=2.55seconds .

Also notice that, since the acceleration is constant, we can easily find the average velocity.

∴vaverage=vinitial+vfinal2=25+02=12.5m/s

Since we know the average velocity during the entire journey and the time of flight, we can find the total distance travelled, or to phrase it properly, the height. Since total distance is average velocity times the time of flight, so naturally it follows that

Height=vaverage∗Δt=12.5∗259.8=31.89m■