Homework Help: physics

Posted by parul on Monday, May 28, 2012 at 2:35am.

a body moves with a uniform velocity of 2m/sec for 5 sec then velocity was uniformly accelerated and a velocity of 10m/sec was achieved in next 5 sec.then brakes were applied uniformly and body comes to rest in next 10 sec.calculate
a)acceleration and retardation produced
b)distance moved by the body with uniform velocity
c)different distances moved by the body with non-uniform velocity i.e.when acceleration was active
d)average velocity in whole journey

physics - Elena, Monday, May 28, 2012 at 8:50am
s1=v1•t1 =2•5 =10 m.

v2=v1+a1•t2 .
a1 =(v2-v1)/t2 =( 10-5)/5 = 1m/s².
s2 = v1•t2 + a1•t2²/2 =5•5+1•25/2 =37.5 m.

0 =v2+a2•t3,
a2 =(0-v2)/t3 = -10/10 =-1 m/s².
s3 = v2•t3 – a2•t3²/2 =10•10-1•100/2 =50 m

v(ave_ =s/t =(s1+s2+s3)/(t1+t2+t3) =
(10+37.5+50)/(5+5+10) = 97.5/20 =4.875 m/s

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