While catching a cricket ball of mass 0.2 kg moving with the speed of 20 m/s . The player draws his hand backward through 20 cm. Find the work done in catching the ball ?
Answers
Answer:
Work done in catching ball = -40 J
Step by step explanations:
Given that,
a cricket ball of mass 0.2 kg moving with the speed of 20 m/s
here,
initial velocity of the ball = 20 m/s
A player catches the ball and draws his hand backward through 20 cm
so,
final velocity of the ball will 0 m/s
distance travelled will retardation in hand = 20 cm = 0.2 m
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FIRST METHOD
NEWTON'S LAW
now we have,
initial velocity (u) = 20 m/s
final velocity(v) = 0 m/s
distance travelled (s) = 0.2 m
by the equation of motion
v² = u² + 2as
putting the values,
0 = 20² + 2a(0.2)
0.4a = -400
a = -400/0.4
a = -1000 N
acceleration of the ball = -1000 m/s²
mass of the ball = 0.2 kg
so,
force applied on ball
= mass × acceleration
= 0.2 × -1000
Force = -200 N
NOTE : Negation of force shows the displacement against the motion .
now,
we have
Force(F) = -200 N
displacement(S)= 0.2 m
so,
Work done in catching ball = FS
= -200 × 0.2
= -40 J
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SECONDS METHOD
WORK ENERGY THEOREM
By the work energy theorem
work done = change in kinetic energy
so,
work done = ½ m(v² - u²)
putting the values,
work done = ½ × 0.2(0 - 20²)
= 0.1(-400)
= -40 J
so,
Work done in catching ball = -40 J
Answer:
Work done in catching ball = -40 J
Step by step explanations:
Given,
initial velocity of the ball = 20 m/s
final velocity of the ball will 0 m/s
distance travelled by ball in hand = 20 cm = 0.2 m
By the Work energy theorem
work done = ΔK
work done = ½ m(v² - u²)
= ½ × 0.2(0 - 20²)
= 0.1(-400)
= -40 J
so,