9. An elevator has a mass of 1900 kg. Calculate the power required to lift it a

Question

9. An elevator has a mass of 1900 kg. Calculate the power required to lift it a vertical distance 50 m in a time of 20 s if there is a constant frictional force of 1750 N. a. 22 kW b. 39 kW c. 92 kW d. 51 kW e. 75 kW

10. A ball of mass M traveling at 10:0 m=s makes a head-on, elastic collision with a second ball of mass 2M that is initially at rest. After the collision, the Örst ball (of mass M) will have a velocity of a. 3:3 m=s b. 5:8 m=s c. 7:4 m=s d. 0:12 m=s e. 1:4 m=s

11. A 720 N force is applied to a 120 gm ball for a time of 0:25 s. Calculate its momentum assuming it was initially at rest. a. 110 kg m=s b. 73 kg m=s c. 60 kg m=s d. 35 kg m=s e. 180 kg m=s

12. A truck has a mass of 4820 kg and a wheelbase (distance between front and rear wheels) of 4:8 m. If the center of mass of the truck is located 1:9 m behind the front wheels, where should a 5450 kg load be placed (relative to the front wheels) in order to have equal weight on both sets of wheels? a. 2:4 m b. 1:9 m c. 3:1 m d. 2:8 m e. 1:6 m

Please answer and show all work, will rate highly. thanks

Explanation / Answer

9. power P = mgh/t

here Net force = mg - 1750

Force = 1900*9.8 + 1750 =20370N

P = 20370 * 50/20

P = 51 kN , option d it is

--------------------------------

10. use m1u1 + m2u2 = m1v1 + m2v2

V1 = 2(m2 -m1)u1/(m1+m2)

V2 = 2* M * 10/( 2M)

V2 = 10-6.67 = 3.3 m/s option A it is

----------------------------------------

11. Impulse = change in momentum = F t

M v = 720 * 0.25

MV = 180 kgm/s

option e it is

------------------------------------------------

use the equation

F(0) + F(4.8) - 4820 * (4.8/2) - (5450*X) = 0

x = 2.4 M

option A it is

Related Questions

Navigate

• Browse (All)
• Browse 9
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.