DATE:NAME:CLASS:

Chapter 1

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Section 1.2

Warm-up Problems

Warm-up problems for student textbook page 18

1.A car accelerates from rest to 60 km/h in 4.0 s. Determine the acceleration of the car, assuming that it is constant.

2.The car in question 1 has a mass of 2000 kg. Determine the net force acting on it.

3.The driver of a car travelling at a speed of 50 km/h slams on the brakes, producing an acceleration of 12 m/s2. How far does the car travel before stopping?

4.A braking system for a roller coaster is designed to stop it over a distance of 15 m when the coaster enters the stopping area with a speed of 40 km/h. What acceleration must the braking system provide?

Warm-up problems for student textbook pages 21–22

1.A curling stone has an initial speed of 0.885 m/s and stops after 71.2 s.
(a) Determine the acceleration of the stone.
(b) Determine the distance travelled by the stone.

2.Movers drag a deep freezer of mass 180 kg across a floor at a constant speed by applying a force of 400 N. Determine the coefficient of kinetic friction between the freezer and the ground.

3.The mass of a loaded wheelbarrow is 50 kg and the coefficient of kinetic friction between its wheel and the ground is 0.9. What is the horizontal component of force that must be applied to the wheelbarrow to keep it moving at a constant speed?

4.A cyclist coasts down a hill at a constant speed without using the pedals. The total mass of the bicycle and cyclist is 90 kg and the hill makes an angle of 10º with the horizontal. What is the coefficient of kinetic friction between the bicycle and the hill?

Warm-up problems for student textbook pages 25–26

1.A formal dining hall has a chandelier of mass 60 kg hanging from a cable attached to the ceiling. A second chandelier of mass 100 kg hangs by a cable from the first chandelier. Determine the tension in each cable.

2.A tractor with two trailers moves at a constant speed on a straight level road. The mass of the tractor is 5000 kg and the mass of each trailer is 25 000 kg. Determine the force exerted by each of the two trailer hitches.

3.Repeat exercise 2 if the tractor-trailer is accelerating at 2 m/s2.

4.Repeat exercise 3 if the coefficient of kinetic friction between the tires and the road is 0.7.

Copyright © 2002 McGraw-Hill Ryerson Limited

DATE:NAME:CLASS:

Chapter 1

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Section 1.3
Warm-up Problems

Warm-up problems for student textbook page 30

1.Determine the weight of a person that has a mass of a) 50 kg b) 60 kg c) 70 kg.

2.Determine the mass of a person that has a weight of a) 400 N b) 550 N c) 800 N.

3.Determine the direction of the acceleration and its sign in each case.

(a)An elevator speeds up as it begins to descend.

(b)An elevator slows down as it nears the bottom of its descent.

(c)An elevator speeds up as it begins to ascend.

(d)An elevator slows down as it nears the top of its ascent.

4.A person is standing on a scale in an elevator. The scale reads 50 kg. Describe the kinds of motion of the elevator for which the reading on the scale will be

(a)greater than 50 kg.

(b)less than 50 kg.

Warm-up problems for student textbook page 32

1.At a construction site, a load of lumber of mass 200 kg is suspended at rest from a cable attached to a crane. Determine the tension in the cable.

2.Determine the tension in the cable of question 1 if the load of lumber is being

(a)raised at a constant speed.

(b)lowered at a constant speed.

(c)accelerated upward, and the magnitude of the acceleration is 0.5 m/s2.

(d)accelerated downward, and the magnitude of the acceleration is 0.7 m/s2.

3.The cable in question 1 will break if its tension exceeds 5000 N.

(a)For a load being raised upward, what is the maximum allowable upward acceleration for which the cable does not break?

(b)For a load being lowered, what is the maximum allowable downward acceleration for which the cable does not break?

4.Describe how the tension in a bungee cord changes as a rider is dropped, travels downward, reaches the lowest point of the journey, rises back up, and reaches the highest point of the journey.

Warm-up problems for student textbook page 38

1.A crane hauls a load of brick upward with an acceleration whose magnitude is 1 m/s2. If the mass of the load is 250 kg, determine the tension in the cable.

2.A bridge counterweight is pulled upward by a cable whose tension is 50 000 N. If the mass of the counterweight is 4000 kg, determine its acceleration.

3.An Atwood machine consists of two equal masses of 5 kg each. If the system is at rest, determine the tension in the rope connecting the masses.

4.In the system of question 1, the rope suddenly breaks. Determine the tension in each part of the broken rope, and determine the acceleration of each mass.

Warm-up problems for student textbook page 41

1.A 150 g cart sliding on a frictionless horizontal table is attached to a suspended mass by a string passing over a pulley. Determine the suspended mass if the acceleration of the cart is 0.5 m/s2?

2.A mining machine moving on a horizontal shaft is attached to a suspended bucket by a cable passing over a pulley. The bucket has a mass of 250 kg and moves in a vertical shaft. If the bucket is to be accelerated upward at a rate of 0.3 m/s2, determine the tension in the cable.

3.A 200 g cart sliding on a frictionless horizontal table is attached to a suspended 120 g mass by a string passing over a pulley. Determine the tension in the string and the acceleration of the masses.

4.Repeat question 3 if the coefficient of kinetic friction between the cart and the table is 0.2.

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DATE:NAME:CLASS:

Chapter 1

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Section 1.4
Warm-up Problems

Warm-up problems for student textbook page 49

1.A 2300 kg car rolls down a hill inclined at an angle of 10º. Assuming that there is no friction, what is the acceleration of the car?

2.Determine the acceleration in question 1 if the coefficient of kinetic friction is 0.7.

3.A water slide 4 m long is inclined at an angle of 30º. Assume that there is no friction.

(a)What is the acceleration of a child sliding down the water slide?

(b)Assuming that a child starts from rest at the top of the water slide, what is the child’s speed when it reaches the bottom of the water slide?

(c)How long is the child in the water slide?

4.Repeat question 3 if the child has a mass of 30 kg and the coefficient of kinetic friction between the child and the slide
is 0.1.

Warm-up problems for student textbook page 51

1.A skateboarder rolls down a ramp at a constant speed. The inclination of the ramp is 20º and the total mass of the skateboarder and skateboard is 60 kg. Determine the coefficient of kinetic friction.

2.A tow rope pulls a 60 kg skier up a hill that is inclined at an angle of 35º. If the hill is assumed to be frictionless, determine the tension in the tow rope.

3.A refrigerator is being hauled up a ramp at a constant speed. The tension in the hauling rope is 2000 N, the mass of the refrigerator is 120 kg, and the inclination of the ramp is 25º. Determine the coefficient of friction between the refrigerator and the ramp.

4.Suppose that the rope in question 3 suddenly breaks. Will the refrigerator slide down the ramp, and if so, with what acceleration?

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Chapter 1

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Chapter Review
Warm-up Problems

Warm-up problems for student textbook pages 52–55

1.The total force acting on a 115 g ball is 245 N. Determine the ball’s acceleration.

2.Determine the gravitational force acting on a 68 kg person.

3.A car accelerates from 20 km/h to 55 km/h in 8 s. Determine how far the car travels in this time, assuming that the acceleration is constant.

4.A car accelerates from 30 km/h to 80 km/h over a distance of 800 m. Determine the car’s acceleration, assuming that it is constant.

Copyright © 2002 McGraw-Hill Ryerson Limited

Answers

Chapter 1

Section 1.2

Warm-up problems for student textbook page 18

1.4.2 m/s2

2.8400 N

3.100 m

4.4.1 m/s2

Warm-up problems for student textbook pages 21–22

1.(a) 0.012 m/s2(b) 32.6 m

2.0.23

3.440 N

4.0.18

Warm-up problems for student textbook pages 25–26

1. 1600 N, 980 N

2.0, 0

3.100 000 N, 50 000 N

4.443 000 N, 221 500 N

Section 1.3

Warm-up problems for student textbook page 30

1.(a) 490 N(b) 590 N(c) 690 N

2.(a) 41 kg(b) 56 kg(c) 82 kg

3.(a) downward, negative(b) upward, positive(c) upward, positive(d) downward, negative

4.(a) moving upward and speeding up, or moving downward and slowing down (b) moving upward and slowing down, or moving downward and speeding up

Warm-up problems for student textbook page 32

1.1960 N

2.(a) 1960 N(b) 1960 N(c) 2060 N(d) 1820 N

3.(a) 15.2 m/s2(b) The cable will not break even if the load is allowed to fall freely.

4.The tension in the cord increases as the rider falls, and continues to increase on the way up as long as the rider accelerates upward. When the rider begins to slow down on the upward journey the tension decreases, and may reach zero.

Warm-up problems for student textbook page 38

1.2700 N

2.2.7 m/s2

3.49 N

4.0 N, 9.8 m/s2

Warm-up problems for student textbook page 41

1.8 g

2.2525 N

3.0.735 N, 3.68 m/s2

4.0.882 N, 2.45 m/s2

Copyright © 2002 McGraw-Hill Ryerson Limited

Section 1.4

Warm-up problems for student textbook page 49

1.1.7 m/s2

2.0

3.(a) 4.9 m/s2(b) 6.3 m/s(c) 1.3 s

4.(a) 4.1 m/s2(b) 5.7 m/s(c) 1.4 s

Warm-up problems for student textbook page 51

1.0.36

2.340 N

3.1.4

4.No

Chapter Review

Warm-up problems for student textbook pages 52–55

1.2.13 km/s

2.670 N

3.80 m

4.0.27 m/s2

Copyright © 2002 McGraw-Hill Ryerson Limited