Question

# A weight lifter raises a barbell of mass 72 kg to a height of 0.65 m...

A weight lifter raises a barbell of mass 72 kg to a height of 0.65 m above his chest. The potential energy of the barbell increases in raising the barbell by approximately

Select one:

a. 459 J

b. Zero

c. –459 J

d. None of these

Three masses 2.0 kg, 3.0 kg and 6.0 kg are located at positions (3.0, 0), (6.0, 0), and (–4.0, 0), respectively, in meters from the origin (0,0). The location of the center of mass of this system is

Select one:

a. (0, 0)

b. (–1, 0)

c. (5, 0)

d. (0, –1)

A 0.1 kg steel ball is dropped straight down onto a hard horizontal floor and bounces straight up. Its speed just before and just after impact with the floor is 10 m/s. Determine the magnitude of the impulse delivered to the floor by the steel ball.

Select one:

a. 2 N.s

b. 1 N.s

c. 10 N.s

d. zero

Use the work-energy theorem to find how much net work required to accelerate a 1000 kg car from 20 m/s to 30 m/s.

Select one:

a. 2.6 X 10^4 J

b. 8.2 X 10^3J

c. 2.5 X 10^5 J

d. 1.9 X 10^5 J

A system consisting of two particles, one of which is moving to the east with a momentum of 7.0 kg.m/s while the other particle is moving to the west with a momentum of 3 kg.m/s. The total momentum (magnitude and direction) of the system is

Select one:

a. 4.0 kg.m/s, east

b. 4.0 kg.m/s, west

c. -4.0 kg.m/s, east

d. 10 kg.m/s, east

A 50 kg boy runs at a speed of 10.0 m/s and jumps onto a small cart. The cart is initially at rest. If the mass of the cart is 150 kg, what is the speed of the cart with the boy?

Select one:

a. 175 kg

b. 6.0 m/s

c. 2.5 m/s

d. 2.0 m/s

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