Ch-4

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Ch-4

• Help-Session

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CH-4-072

• Q9 A projectile is fired over a flat horizontal
  land. It takes 10 s to reach its range of 100 m.
  What is the speed of the projectile at the
  highest point of its trajectory?

• Q10. A particle is moving counterclockwise in
  x-y plane in a uniform circular motion. The
  circle is centered at the origin and has a radius
  of 2.0 m. When the velocity of the particle is
  4i m/s , then its acceleration is

• x1vitat2/2
• av2 /R16/28 m/s2
• Particle is in at beginning of fourth Quadrant
  of circle, a towards center i.e. j
• a (8 m/s2) j

At maximum height h v v0xivyj vy0 v0x
R/t100/1010 m/s v v0xi (10 m/s )i
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CH-4-072
Q12. A particle has its position vector defined
by R(2.ot-t2)i(3.0t-1.5t2)j. At what time is
its speed equal to zero? (Ans 1.0 s)

• Q11. A river is flowing 0.20 m/s east. A boat in
  this river has a speed of 0.40 m/s directed 60
  south of east relative to the earth. Find the
  velocity of the boat relative to the river.

• Angle between vbw and vbg90-6030
• vbwvbg cos 300.4 cos 300.346 m/s

vdr/dt(2-2t)i(3-3t)j To calculate t for
v0 Equate quotient of i and j separately to
Zero we get 2-2t0 t1 3-3t0 t1
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CH-4-071
T071  Q10.A certain airplane has a speed of
80.6 m/s and is diving at an angle of 30.0 below
the horizontal when it releases an object. The
horizontal distance from the point of release was
300 m as shown in Fig.4. How high was the point
of release of the object? (Ans 264 m)
Q11. An object is moving on a circular path of
radius p meters at a constant speed of 4.0 m/s.
The time required for one revolution is (Ans
(p2/2) s)
T(2pR)/v(2pp)/4 (pp)/2
Time t for x-motion 300/(80.6cos30)
4.30 s -h-80.6sin304.3-0.59.84.3
4.3 -173.3-90.6-263.9 m h 264 m
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CH-4-071
Q12. Ship A travels 40 km/h in a direction of
30 West of North and ship B travels 60 East of
North at 30 km/h. What is the magnitude of the
velocity of ship A relative to ship B?( Ans 50
km/h)
vBG 30 cos 60 i-30sin60j 15i-26j vAG -40
cos 30i-40 sin 30j -34.6i-20j vAG - vBG
(-34.6-15)i-(20-26)j -49.6 I
6j vAG - vBG ?49.6262 49.96 m/s