Applying Newton’s Laws

Applying Newton’s Laws.

I need an explanation for this Physics question to help me study.

1-

A 9.00-

kg



k


g


block of ice, released from rest at the top of a 1.09-

m



m


-long frictionless ramp, slides downhill, reaching a speed of 2.94

m/s




m



/



s



at the bottom.

Part A

What is the angle between the ramp and the horizontal?

Part B

What would be the speed of the ice at the bottom if the motion were opposed by a constant friction force of 10.1

N




N



parallel to the surface of the ramp?



v


v

=

nothing



m/s

2-

A stockroom worker pushes a box with mass

12.0


kg




k


g


on a horizontal surface with a constant speed of

3.30


m/s




m



/



s


. The coefIficient of kinetic friction between the box and the surface is

0.25.

Part A

What horizontal force must the worker apply to maintain the motion?

Express your answer with the appropriate units.



F


F

=

3-

A 50.0

kg




k


g



ice skater spins about a vertical axis through her body with her arms horizontally outstretched, making 2.00 turns each second. The distance from one hand to the other is 1.5

m



m


. Biometric measurements indicate that each hand typically makes up about 1.25

%


%

of body weight.

Part A

What horizontal force must her wrist exert on her hand?



F


F

=



N



N


SubmitPrevious AnswersRequest Answer

Part B

Express the force in part (a) as a multiple of the weight of her hand.



F


F

=

w




.

4-o-

A rocket of initial mass

135


kg




k


g


(including all the contents) has an engine that produces a constant vertical force (the thrust) of

1710


N




N


. Inside this rocket, a

12.5-


N



N


electrical power supply rests on the floor.

Part A

Part complete

Find the initial acceleration of the rocket.

Express your answer with the appropriate units.



ainitial



a



i


n


i


t


i


a


l



=

2.87

ms2






m



s



2







SubmitPrevious Answers

Correct

Part B

When the rocket has reached an altitude of

120


m



m


, how hard does the floor push on the power supply? Neglect the air resistance.

Express your answer with the appropriate units.



N


N

=


5–o—

A 8.60-

kg



k


g


block of ice, released from rest at the top of a 1.37-

m



m


-long frictionless ramp, slides downhill, reaching a speed of 2.86

m/s




m



/



s



at the bottom.

Part A

What is the angle between the ramp and the horizontal?



ϕ


ϕ

=










Part B

What would be the speed of the ice at the bottom if the motion were opposed by a constant friction force of 10.6

N




N



parallel to the surface of the ramp?



v


v

=

nothing



m/s



m



/



s



Applying Newton’s Laws

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