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20.A bullet loses 1/20 of its velocity on passing through a plank. The least number of planks required to stop the bullet is

solution: velocity of bullet after passing from plank ,its velocity decreases . initial velocity(u)=u final velocity(v)=initial velocity-1/20 of initial velocity v=u-u/20 v=19u/20 we have formula for one plank, (v)2-(u)2=2as, (19u/20)2-(u)2=2as 39u2/400=2as ……….(1) for n planks: then width of one plank will be ‘s’ width of n planks will be ns after passing from n planks …

20.A bullet loses 1/20 of its velocity on passing through a plank. The least number of planks required to stop the bullet is Read More »

21.ఉపాధ్యాయులకు టెట్ తప్పనిసరి అని విద్య శాఖ నిర్ణయం

రాష్ట్రంలో ప్రభుత్వ ఉపాధ్యాయులు పదోన్నతి పొందాలంటే టెట్ ఉతీర్ణులు కావడం తప్పనిసరి సర్కారు తుది నిర్ణయానికి వచ్చింది.

19.A car initially at rest starts with a uniform acceleration and gains a velocity of 20m/s in 4s.The displacement of the car is

solution: a car initially starts at rest (u)=0 it is moving with uniform acceleration and the car gains velocity(v)=20m/s. the time taken by the car is (t)=4s we have the formula v=u+ at 20=0+4a 20=4a a=5m/s2 we got the uniform acceleration a =5m/s2 then ,for displacement S=ut+1/2at2 =0*4+1/2*5*4*4 =1/2*5*2*4 =40m or displacement=(u+v)/2*t =(0+20)/2*4 =40m The …

19.A car initially at rest starts with a uniform acceleration and gains a velocity of 20m/s in 4s.The displacement of the car is Read More »

17.A car accelerates from rest at a constant rate α for sometime and reaches a maximum velocity. Then at decelerates rate β to come to rest. If the time lapsed is ‘t’ ,then the maximum velocity acquired by the will be

solution: The car starts from rest (u)=0 acceleration (a)=α to reach maximum velocity “V1“ then ,the car decelerates with (a)=-β final velocity (V2)=0 for the first case ,V1=0+αt1,t1=V1/α for the second case, initial velocity(u)=V1 with deceleration (a)=-β final velocityV2 =0 0=V1-βt2 V1=βt2,t2=V1/β Total time=V1/α+V1/β=V1(β+α)/αβ=V1=(αβ/α+β)t V1=(αβ/α+β)t

15.An object projected vertically upwards with an initial velocity 40m/s from the ground(g=10m/s2).The time taken by the object to reach the maximum height

solution: The object projected vertically upwards an initial velocity(u)=40m/s if the object to reach the maximum height, the final velocity will be zero. from kinematic equations ,we have the formula, (v)2-(u)2=2as here , v=0,u=40m/s, a=-g=10m/s2 0-40*40=2(-10)S -1600=-20S S=80m here, distance is nothing but maximum height .

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