Questions and Answers of University Physics

People who do chin-ups raise their chin just over a bar (the chinning bar), supporting themselves with only their arms. Typically, the body below the arms is raised by about 30 cm in a time of 1.0 s,
While a person is walking, his arms swing through approximately a 45° angle in ½ s. As a reasonable approximation, we can assume that the arm moves with constant speed during each swing. A typical
Consider the system shown in Fig. E5.34. Block A weighs 45.0 N and block B weighs 25.0 N. Once block B is set into downward motion, it descends at a constant speed.(a) Calculate the coefficient of
A pickup truck is carrying a toolbox, but the rear gate of the truck is missing, so the box will slide out if it is set moving. The coefficients of kinetic and static friction between the box and the
Some sliding rocks approach the base of a hill with a speed of 12 m/s. The hill rises at 36° above the horizontal and has coefficients of kinetic and static friction of 0.45 and 0.65, respectively,
In emergencies with major blood loss, the doctor will order the patient placed in the Trendelenburg position, in which the foot of the bed is raised to get maximum blood flow to the brain. If the
A 5.00-kg crate is suspended from the end of a short vertical rope of negligible mass. An upward force F(t) is applied to the end of the rope, and the height of the crate above its initial position
A 2.00-kg box is moving to the right with speed on a horizontal, friction less surface. At a horizontal force is applied to the box. The force is directed to the left and has magnitude F(t) = (6.00
An average person can reach a maximum height of about 60 cm when jumping straight up from a crouched position. During the jump itself, the person’s body from the knees up typically rises a distance
Three sleds are being pulled horizontally on friction less horizontal ice using horizontal ropes (Fig. E5.14). The pull is of magnitude 125 N. Find(a) The acceleration of the system and(b) The
An astronaut is inside a 2.25 × 106 kg rocket that is blasting off vertically from the launch pad. You want this rocket to reach the speed of sound (331 m/s) as quickly as possible, but you also do
In the treatment of spine injuries, it is often necessary to provide some tension along the spinal column to stretch the backbone. One device for doing this is the Stryker frame, illustrated in Fig.
Sam heaves a 16-lb shot straight upward, giving it a constant upward acceleration from rest of 35.0 m/s2 for 64.0 cm. He releases it 2.20 m above the ground.You may ignore air resistance.(a) What is
On Planet X, you drop a 25-kg stone from rest and measure its speed at various times. Then you use the data you obtained to construct a graph of its speed as a function of time t (Fig. P2.78). From
All the stars of the Big Dipper (part of the constellation Ursa Major) may appear to be the same distance from the earth, but in fact they are very far from each other. Figure P1.101 shows the
The Mars Polar Lander spacecraft was launched on January 3, 1999. On December 3, 1999, the day Mars Polar Lander touched down on the Martian surface, the positions of the earth and Mars were given by
The scalar product of vectors A and B is +48.0 m2. Vector A has magnitude 9.00 m and direction 28.0o west of south. If vector B has direction 39.0o south of east, what is the magnitude of B?
Vector A has magnitude 6.00 m and vector B has magnitude 3.00 m. The vector product between these two vectors has magnitude 12.0 m2. What are the two possible values for the scalar product of these
When two vectors A and B are drawn from a common point, the angle between them is É¸.(a) Using vector techniques, show that the magnitude of their vector sum is given by(b) If A and B
Vector A has magnitude 12.0 m and vector B has magnitude 16.0 m. The scalar product A ∙ B is 90.0 m2. What is the magnitude of the vector product between these two vectors?
Vectors A and B have scalar product -6.00 and their vector product has magnitude +9.00. What is the angle between these two vectors?
John, Paul, and George are standing in a strawberry field. Paul is 14.0 m due west of John. George is 36.0 m from Paul, in a direction 37.0o south of east from Paul’s location. How far is George
Ricardo and Jane are standing under a tree in the middle of a pasture. An argument ensues, and they walk away in different directions. Ricardo walks 26.0 m in a direction 60.0o west of north. Jane
A dog in an open field runs 12.0 m east and then 28.0 m in a direction 50.0o west of north. In what direction and how far must the dog then run to end up 10.0 m south of her original starting point?
A fence post is 52.0 m from where you are standing, in a direction 37.0o north of east. A second fence post is due south from you. What is the distance of the second post from you, if the distance
We say an object is in equilibrium if all the forces on it balance (add up to zero). Figure P1.75 shows a beam weighing 124 N that is supported in equilibrium by a 100.0-N pull and a force F at the
Dislocated Shoulder. A patient with a dislocated shoulder is put into a traction apparatus as shown in Fig. P1.73. The pulls and have equal magnitudes and must combine to produce an outward traction
A rocket fires two engines simultaneously. One produces a thrust of 480 N directly forward, while the other gives a 513-N thrust at 32.4o above the forward direction. Find the magnitude and direction
(a) Find the magnitude and direction of the vector R that is the sum of the three vectors A, B, and C in Fig. E1.28. In a diagram, show how is formed from these three vectors.(b) Find the magnitude
Three horizontal ropes pull on a large stone stuck in the ground, producing the vector forces A, B, and C shown in Fig. P1.66. Find the magnitude and direction of a fourth force on the stone that
Two workers pull horizontally on a heavy box, but one pulls twice as hard as the other. The larger pull is directed at 25.0° west of north, and the resultant of these two pulls is 460.0 N directly
A rectangular piece of aluminum is 7.60 ± 0.01 cm long and 1.90 ± 0.01 cm wide.(a) Find the area of the rectangle and the uncertainty in the area.(b) Verify that the fractional uncertainty in the
Vector A is 2.80 cm long and is 60.0oabove the x-axis in the first quadrant. Vector is 1.90 cm long and is below the x-axis in the fourth quadrant (Fig. E1.39). Use components to find the
A disoriented physics professor drives 3.25 km north, then 2.90 km west, and then 1.50 km south. Find the magnitude and direction of the resultant displacement, using the method of components. In a
Vector A is in the direction 34.0o clockwise from the –y-axis. The x-component of A is Ax = – 16.0 m.(a) What is the of A?(b) What is the magnitude of A?
Vector A has y-component Ay = +13.0 m. A makes an angle of 32.0o counterclockwise from the y-axis.(a) What is the x-component of A?(b) What is the magnitude of A?
Compute the x- and y-components of the vectors A, B, C, and D in Fig. E1.28.Figure E1.28: B (15.0 m) 30.0 ° Ď (10.0 m) 53.0 25.0 Ċ (12.0 m) VÄ (8.00 m)
(a) The recommended daily allowance (RDA) of the trace metal magnesium is 410 mg/day for males. Express this quantity in μg/day.(b) For adults, the RDA of the amino acid lysine is 12 mg per kg of
Breathing Oxygen. The density of air under standard laboratory conditions 1.29 kg/m3 is and about 20% of that air consists of oxygen. Typically, people breathe about ½ L of air per breath.(a) How

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