7.)A 2 400-kg pile driver is used to drive a steel I-beam into the ground. The p

Question

7.)A 2 400-kg pile driver is used to drive a steel I-beam into the ground. The pile driver falls 3.80 m before coming into contact with the top of the beam, and it drives the beam 15.0 cm farther into the ground before coming to rest. Using energy considerations, calculate the average force the beam exerts on the pile driver while the pile driver is brought to rest.

14.)A sled of mass m is given a kick on a frozen pond. The kick imparts to it an initial speed of 2.90 m/s. The coefficient of kinetic friction between sled and ice is 0.150. Use energy considerations to find the distance the sled moves before it stops.
m

17.)Calculate the power a car engine contributes to speeding the 2100 kg car up to a highway speed of 65.0 mi/h in 13.0 s.
hp

Explanation / Answer

Given

vectors A = 1 i + 2j - 5k

B = -3i +4j +k

C = 0i +5j -5k

first calculating (A - B)

(A-B) = (1 i + 2j - 5k )-(-3i +4j +k )

= (1+3) i +(2-4) j + (-5-1) k

= 4i -2j -6 k

now C.(A-B) = (0i +5j -5k )(4i -2j -6 k)

= (0*4)(i.i) + (5*(-2))(j.j)+((-5)(-6))(k.k)

= 0*1 +(-10*1) +30*1

= 0 -10+30 = 20

C.(A-B) = 20

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