Problem 7.21 A 87-kg fullback is running at 3.1 m/s to the east and is stopped i
ID: 1556586 • Letter: P
Question
Problem 7.21
A 87-kg fullback is running at 3.1 m/s to the east and is stopped in 0.85 s by a head-on tackle by a tackler running due west.
Part A
Calculate the original momentum of the fullback.
Express your answer to two significant figures and include the appropriate units. Enter positive value if the direction of the momentum is to the east, and negative value if the direction of the momentum is to the west.
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Part B
Calculate the impulse exerted on the fullback.
Express your answer to two significant figures and include the appropriate units. Enter positive value if the direction of the impulse is to the east, and negative value if the direction of the impulse is to the west.
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Part C
Calculate the impulse exerted on the tackler.
Express your answer to two significant figures and include the appropriate units. Enter positive value if the direction of the impulse is to the east, and negative value if the direction of the impulse is to the west.
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Part D
Calculate the average force exerted on the tackler.
Express your answer to two significant figures and include the appropriate units. Enter positive value if the direction of the force is to the east, and negative value if the direction of the force is to the west.
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Problem 7.21
A 87-kg fullback is running at 3.1 m/s to the east and is stopped in 0.85 s by a head-on tackle by a tackler running due west.
Part A
Calculate the original momentum of the fullback.
Express your answer to two significant figures and include the appropriate units. Enter positive value if the direction of the momentum is to the east, and negative value if the direction of the momentum is to the west.
p0 =SubmitMy AnswersGive Up
Part B
Calculate the impulse exerted on the fullback.
Express your answer to two significant figures and include the appropriate units. Enter positive value if the direction of the impulse is to the east, and negative value if the direction of the impulse is to the west.
(F¯t)fullback =SubmitMy AnswersGive Up
Part C
Calculate the impulse exerted on the tackler.
Express your answer to two significant figures and include the appropriate units. Enter positive value if the direction of the impulse is to the east, and negative value if the direction of the impulse is to the west.
(F¯t)tackler =SubmitMy AnswersGive Up
Part D
Calculate the average force exerted on the tackler.
Express your answer to two significant figures and include the appropriate units. Enter positive value if the direction of the force is to the east, and negative value if the direction of the force is to the west.
F¯ =SubmitMy AnswersGive Up
Explanation / Answer
A)
m1=87kg, v1i=3.1m/s, v1f=0m/s, t=0.85s
pi=m1*v1i=87*3.1=269.7kg*m/s
B)
Pf = m1*v1f=87*0= 0 kg*m/s
Pfullback = Pf-Pi = 0kg8m/s-269.7kg*m/s = -269.7 kg*m/s
D)
Average force exerted on fullback = Ffullback = P/t = (Pf-Pi)/t = (0-269.7)/0.85 = -317.3 N ………………directed opposite to its initial velocity/ to west
By Newton’s 3rd law
Ftackler = Ffullback
Ftackler = -(-317.3)N = 317.3N………..towards east
C)
Ptackler = Ftackler*t = 317.3*0.85 = 269.7 kg*m/s