ES 422 Quiz 3

•Power is equal to
•a. the amount of force a muscle can generate
•b. force times distance
•c. work
•d. force times displacement divided by time
•e. none of the above

•d. force times displacement divided by time

•Jill's bocci ball rolls with a velocity of 1 m/s, while Jack's rolls with a velocity of 2 m/s in the same direction. Both balls have the same mass. A 10 N average force stops Jill's ball in a distance of 1 m. How big is the average force required to stop Jack's ball over the same 1 m distance?

40N

•Bill lifts a 1000 N barbell 1.5 m in 1.0 s, while Bob lifts a 1400 N barbell 2.0 m in 2.0 s. Whose lift was more powerful?

Bill's lift was more powerful (1500 W versus 1400 W).

Kevin dunks the basketball and then lands safely on two feet. During the landing, most of his leg muscles do \__________ work and undergo \__________ contractions.

negative, eccentric

Power is defined as

a. the product of force and displacement
b. the quotient of force and displacement
c. the rate of change of torque
d. the rate of doing work
e. none of the above

d. the rate of doing work

The form of energy associated with the stiffness and deformability of an object is called

a. gravitational potential energy
b. kinetic energy
c. strain energy
d. molecular energy
e. none of the above

c. strain energy

Mechanical work is performed in all of these types of muscle activity (contraction) except for

a. isometric
b. concentric
c. eccentric
d. Mechanical work is performed in all of the above.
e. Mechanical work is NOT performed in any of the above.

a. isometric

The force to be considered in calculating the work you perform when climbing up a set of stairs is your

a. mass
b. weight
c. height
d. percent body fat
e. none of the above

b. weight

The difference between positive and negative work stems from the direction of motion of the body the force acts on and the

a. magnitude of the force acting on the body
b. point of application of the force acting on the body
c. line of action of the force acting on the body
d. direction of the force acting on the body
e. There is no difference between positive and negative work.

d. direction of the force acting on the body

When catching a baseball or softball with a glove,

a. the ball performs positive work on the glove, and the glove performs negative work on the ball
b. the ball performs negative work on the glove, and the glove performs positive work on the ball
c. positive work is performed on both the ball and the glove
d. negative work is performed on both the ball and the glove
e. no work is performed since the work on the ball and on the glove cancel each other out

a. the ball performs positive work on the glove, and the glove performs negative work on the ball

In the kinetic energy equation, which component is most important?

a. mass
b. gravity
c. height
d. velocity
e. All components are equally important in the calculation of kinetic energy.

d. velocity

In the equation for calculating strain energy, the x symbolizes

a. stiffness
b. velocity
c. friction
d. a constant
e. the amount of deformation

e. the amount of deformation

What is the gravitational potential energy of a circus performer with a mass of 50 kg walking on a tightrope 10 m above the ground?

a. 5000 Nm
b. 2500 Nm
c. 4210 Nm
d. 5205 Nm
e. need more information to calculate

a. 5000 Nm

A person performs a bench press. The bar's mass is 50 kg. When this person's arms are extended, the bar is 0.6 m above the starting point. How much work did the person do to push the bar off his chest to full extension of his arms?

a. 0 Nm
b. 300 Nm
c. -300 Nm
d. 600 Nm

b. 300 Nm

Kinetic energy is the energy

a. due to deformation
b. due to motion
c. due to position
d. due to weight
e. kids use to run around a room

b. due to motion

Gravitational potential energy is the energy

a. due to deformation
b. due to motion relative to the earth
c. due to position relative to the earth
d. due to weight
e. kids use to run around a room

c. due to position relative to the earth

Strain energy is the energy

a. due to deformation
b. due to motion relative to the earth
c. due to position relative to the earth
d. due to weight
e. kids use to run around a room

a. due to deformation

During an arm wrestling match, your opponent is winning. She is slowly pushing your arm down toward the table. Are you doing any mechanical work against your opponent?

a. yes
b. no
c. need more information to calculate

a. yes

During an arm wrestling match, your opponent is winning. She is slowly pushing your arm down toward the table. If you are doing any mechanical work against your opponent, the work is

a. positive
b. negative
c. No work is being performed.
d. need more information to calculate

b. negative

During the pitching motion, a baseball pitcher exerted an average horizontal force of 80 N against the 0.15 kg baseball while moving it through a horizontal displacement of 2.0 m before release. The amount of work performed by the pitcher on the baseball was
a. 40 J
b. 80 J
c. 82 J
d. 160 J
e. 320 J

d. 160 J

A 25 kg child climbs two steps of 20 cm each in 2 s. The power generated is

a. 0.5 W
b. 5.0 W
c. 50.0 W
d. 500.0 W
e. need more information to calculate

c. 50.0 W

The capacity for doing work that a body possesses because of its position or configuration is known as

a. potential energy
b. kinetic energy
c. moment of inertia
d. power
e. torque

a. potential energy

A soft foam pit is used for landing during the pole vault. The foam pit cushions the landing of the vaulter by

a. reducing the friction encountered
b. reducing the displacement during the landing
c. increasing the friction encountered
d. increasing the displacement during the landing
e. none of the above

d. increasing the displacement during the landing

A 600 N volleyball player lands from a spike attempt and immediately jumps up to try for a block. When she first contacts the ground, her velocity is 3 m/s downward, and then as she leaves the ground for the block her velocity is 4 m/s upward. Her kinetic energy at first contact is

a. 9 J
b. 90 J
c. 180 J
d. 270 J
e. 540 J

d. 270 J

The work-energy principle states that the work done by all the \__________ forces acting on an object (or system of objects) causes a change in total \__________ of the object or system.

a. nonconservative; mechanical energy
b. gravitational; potential energy
c. external; kinetic energy
d. both a and c are correct
e. both b and c are correct

d. both a and c are correct

•Explain the relation between the power duration curve and the force velocity curve.

The duration of the activity establishes a sustainable power output of an individual. A sprinter can only maintain a high power output for about 0-60 s. A mid distance runner's power output is smaller, but sustained longer (1-7 min). A marathoner's power output is even smaller but sustained for way longer.

•When moving outside, whether it is cycling or running the individual needs to produce a total amount of power to overcome
a)Rolling Resistance
b)Air Resistance
c)Gradient
d)All of the above

d)All of the above

•Decreasing weight at a specific power output will increase Efficiency
a)True
b)False

a)True

•The state of matter that makes things change, or has the potential to make thins change is known as
a)Energy
b)Power
c)Work
d)Velocity

a)Energy

•In mechanical energy, kinetic energy is in the form of
a)Linear and angular
b)Gravitational and strain
c)Chemical and thermal
d)Electromagnetic and nuclear

a)Linear and angular

•In mechanical energy, potential energy is in the form of
a)Linear and angular
b)Gravitational and strain
c)Chemical and thermal
d)Electromagnetic and nuclear

b)Gravitational and strain

•Energy stored in a deformed object is known as
a)Strain
b)Potential
c)Thermal
d)Gravitational

a)Strain

•F ̅d \= △KE + △PE This equation is known as the
a)Chemical - Energy Principle
b)Change in Energy
c)Work - Energy Principle
d)Potential - Strain Energy Principle

c)Work - Energy Principle

•The theory where the total mechanical energy of an object stays constant if no external forces other than gravity act on the object is known as...
●
a)Conservation of Potential and Kinetic Energy
b)Conservation of Mechanical Energy
c)Conservation of Thermal Energy
d)Conservation of Work Energy Principle

b)Conservation of Mechanical Energy

•When an object rises up in the air
a)Kinetic energy decreases (velocity decreases)
b)Potential energy increases (height increases)
c)Total energy constant
d)All of the above

d)All of the above

•When a falling object gets closer to the ground
a)Kinetic energy increases (velocity increases)
b)Potential energy decreases (height decreases)
c)Total energy remains constant
d)All of the above
e)Mechanical energy is a joke

d)All of the above

•Total Mechanical Energy Expenditure equation looks at Work in the negative portion as an absolute value
a)True
b)False

a)True

•The amount of mechanical energy that can be expended with a given amount of energy is known as
a)Economy
b)Work
c)Efficiency
d)Energy

c)Efficiency

•The amount of energy required to perform a certain amount of work / mechanical energy is known as
a)Economy
b)Energy
c)Work Conservation
d)Efficiency

a)Economy