A 62.0-kg skier is moving at 6.50 m/s on a frictionless, horizontal, snow-covered plateau when she encounters a rough patch 4.20 m long. The coefficient of kinetic friction between this patch and her skis is 0.300. After crossing the rough patch and returning to friction-free snow, she skis down an icy, frictionless hill 2.50 m high, (a) How fast is the skier moving when she gets to the bottom of the hill? (b) How much internal energy was generated in crossing the rough patch?
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Chapter 7 Solutions
University Physics with Modern Physics (14th Edition)
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An Introduction to Thermal Physics
College Physics (10th Edition)
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Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)
Physics for Scientists and Engineers with Modern Physics
Introduction to Electrodynamics
- If the net work done by external forces on a particle is zero, which of the following statements about the particle must be true? (a) Its velocity is zero. (b) Its velocity is decreased. (c) Its velocity is unchanged. (d) Its speed is unchanged. (e) More information is needed.arrow_forwardAssume that the force of a bow on an arrow behaves like the spring force. In aiming the arrow, an archer pulls the bow back 50 cm and holds it in position with a force of 150 N. If the mass of the arrow is 50 g and the “spring” is massless, what is the speed of the arrow immediately after it leaves the bow?arrow_forwardHow much energy is lost to a dissipative drag force if a 60-kg person falls at a constant speed for 15 meters?arrow_forward
- A 537-kg trailer is hitched to a truck. Find the work done by the truck on the trailer in each of the following cases. Assume rolling friction is negligible. a. The trailer is pulled at constant speed along a level road for 2.30 km. b. The trailer is accelerated from rest to a speed of 88.8 km/h. c. The trailer is pulled at constant speed along a road inclined at 12.5 for 2.30 km.arrow_forwardWhy is the following situation impossible? In a new casino, a supersized pinball machine is introduced. Casino advertising boasts that a professional basketball player can lie on top of the machine and his head and feet will not hang off the edge! The ball launcher in the machine sends metal balls up one side of the machine and then into play. The spring in the launcher (Fig. P6.60) has a force constant of 1.20 N/cm. The surface on which the ball moves is inclined = 10.0 with respect to the horizontal. The spring is initially compressed its maximum distance d = 5.00 cm. A ball of mass 100 g is projected into play by releasing the plunger. Casino visitors find the play of the giant machine quite exciting.arrow_forwardAn 80.0-kg skydiver jumps out of a balloon at an altitude of 1.00 103 m and opens the parachute at an altitude of 200.0 m. (a) Assuming that the total retarding force on the diver is constant at 50.0 N with the parachute closed and constant at 3.60 103 N with the parachute open, what is the speed of the diver when he lands on the ground? (b) Do you think the skydiver will get hurt? Explain. (c) At what height should the parachute be opened so that the final speed of the skydiver when he hits the ground is 5.00 m/s? (d) How realistic is the assumption that the total retarding force is constant? Explain.arrow_forward
- A block of mass m is dropped from the fourth floor of an office building and hits the sidewalk below at speed v. From what floor should the mass be dropped to double that impact speed? (a) the sixth floor (b) the eighth floor (c) the tenth floor (d) the twelfth floor (e) the sixteenth floorarrow_forwardAs shown in Figure P7.20, a green bead of mass 25 g slides along a straight wire. The length of the wire from point to point is 0.600 m, and point is 0.200 in higher than point . A constant friction force of magnitude 0.025 0 N acts on the bead. (a) If the bead is released from rest at point , what is its speed at point ? (b) A red bead of mass 25 g slides along a curved wire, subject to a friction force with the same constant magnitude as that on the green bead. If the green and red beads are released simultaneously from rest at point , which bead reaches point first? Explain. Figure P7.20arrow_forwardA skier is initially moving at 13.7 m/s on level ground as they approach a hill that is angled upward at 15.8 deg. The skier then slides up the hill over a diagonal distance of 5.4 m (assume a coefficient of friction of 0.1). How fast is the skier moving at the top of the hill?arrow_forward
- a mother and her child are skiing together, and the mother is holding the end of a rope tied to the child's waist. They are moving at a speed of 7.2 kph on a gently sloping portion of the ski slope when the morher observes that they are approaching a steep descrnt. She pulls on the rope with an average force of 15 N. Knowing the coefficient of frivtion between the mother and the ground is 0.2, the mass of the mother is 62 kg and the angle of the rope does not change, determine the acceleration of the mother, the time reuired dor the mother's speed to be cut in half, and the distance traveled.arrow_forwardA 2.1 ✕ 103-kg car starts from rest at the top of a 4.7-m-long driveway that is inclined at 21° with the horizontal. If an average friction force of 4.0 ✕ 103 N impedes the motion, find the speed of the car at the bottom of the driveway.arrow_forwarda block is released from rest at height d = 40 cm and slides down a frictionless ramp and onto a first plateau, which has length d and where the coefficient of kinetic friction is 0.50. If the block is still moving, it then slides down a second frictionless ramp through height d/2 and onto a lower plateau, which has length d/2 and where the coefficient of kinetic friction is again 0.50. If the block is still moving, it then slides up a frictionless ramp until it (momentarily) stops. Where does the block stop? If its final stop is on a plateau, state which one and give the distance L from the left edge of that plateau. If the block reaches the ramp, give the height H above the lower plateau where it momentarily stops.arrow_forward
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