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- 1If the acceleration of a car is negative, then ...the car’s velocity must be changing
- 2You throw a ball straight up. At the highest point in the ball's flight...the velocity is zero and the acceleration is downward
- 3The v(t) graph of a bicycle is shown. Which labeled point or segment corresponds to the bicycle having zero acceleration?at B
- 4A driver is going 26 m/s when he sees a sign ahead with a speed limit of 11 m/s. The sign is only 63 m in front of him. What magnitude (absolute value, no negative sign) of acceleration does he need in order to slow to the posted speed limit in time? Enter your answer in m/s2.4.405
- 5A rocket is launched vertically upward. The rocket engines fire as the rocket accelerates upward with constant acceleration until it reaches a height of 290 m, at which point the rocket engines turn off. The rocket coasts upward for another 18 seconds after the engines turn off before reaching its peak height. What was the magnitude of the acceleration of the rocket when the rocket engines were firing?54 m/s^2
- 6A baseball is thrown up and to the left. At the highest point in its flight, the direction of the velocity of the baseball is…left
- 7A baseball is thrown up and to the left. At the highest point in its flight, the direction of the acceleration of the baseball is…down
- 8A rock is thrown with a velocity of 11.6 m/s at an angle of 33° above horizontal. What is the direction (angle) of the velocity when it hits a vertical wall that is 7.3 m from its starting point? Assume that the rock does not hit the ground before hitting the wall.Number not known
- 9A small moving car runs into a large stationary truck. As they collide, which statement about the magnitude of the forces is correct?Ftruck-on-car = Fcar-on-truck > 0
- 10A 15 kg box is moving up a 31° slope at 7 m/s, pushed by a horizontal force of 157 N. The coefficient of kinetic friction between the box and the surface is 0.47. What is the acceleration of the box (both magnitude and direction, direction can be indicated by +/- with a clear set of axes)? Remember that your answer is everything you write (not just your "result") and needs to include all appropriate steps. Upload your work.About 4.814 m/s^2
- 11Two unequal masses collide as shown (larger object has more mass). No other unseen forces are present. The numbers are speeds. The collision shown could not happen because it violates...both conservation of energy and momentum
- 12Two unequal masses collide as shown (larger object has more mass). No other unseen forces are present. The numbers are speeds. The collision shown could not happen because it violates...conservation of momentum
- 13A physics student tries to power his car using a spring rather than gas. He goes to his local home improvement store and buys a spring with a spring constant of 26,000 N/m. How much must the spring be compressed or stretched to store enough energy to get his 1800 kg car up to 19 m/s?5.0 m
- 14A 1800 kg car moving at 19 m/s runs into a stationary 5700 kg truck. After the collision, the car is observed to be moving backward (opposite it’s original velocity) with a speed of 6 m/s. What is the speed of the truck after the collision? Assume that no other horizontal forces are present during the collision. Hint: the collision is not necessarily elastic.7.9 m/s
- 15A 1800 kg car moving at 19 m/s runs into a stationary 5700 kg truck (same as previous question). If the collision were elastic, then the speed of the truck after the collision would have been ...9.1 m/s
- 16When a rigid body rotates about a fixed axis, all the points in the body have the sameangular acceleration.
- 17If the torque on an object adds up to zerothe object could be both turning and accelerating linearly.
- 18A 3.45-kg centrifuge takes 100 s to spin up from rest to its final angular speed with constant angular acceleration. A point located 8.00 cm from the axis of rotation of the centrifuge moves with a speed of 150 m/s when the centrifuge is at full speed. (a) What is the angular acceleration (in rad/s^2) of the centrifuge as it spins up? (b) How many revolutions does the centrifuge make as it goes from rest to its final angular speed?A) 187.5 rad/s
B) 149207.7591 revolutions - 19A restoring force of magnitude F acts on a system with a displacement of magnitude x. In which of the following cases will the system undergo simple harmonic motion?F is proportional to x
- 20The simple harmonic motion of an object is described by the graph shown in the figure. What is the equation for the position x(t) of the object as a function of time t?x(t) = (4.0 m)cos[(2π/8.0 s)t - π/3.0]
- 21If we double only the spring constant of a vibrating ideal mass-and-spring system, the mechanical energy of the systemincreases by a factor of 2.
- 22If you double the pressure on the surface of a can of water, the buoyant force on a stone placed in that water willnot change.
- 23In a section of horizontal pipe with a diameter of 3.00 cm the pressure is 5.21 kPa and water is flowing with a speed of 1.50 m/s. The pipe narrows to 2.50 cm. What is the pressure in the narrower region if water behaves like an ideal fluid of density 1000 kg/m3?4.00 kPa
- 24It is a well-known fact that water has a higher specific heat than iron. Now, consider equal masses of water and iron that are initially in thermal equilibrium. The same amount of heat, 30 calories, is added to each one. Which statement is true?They are no longer in thermal equilibrium; the iron is warmer.
- 25A sample of an ideal gas is slowly compressed to one-half its original volume with no change in temperature. What happens to the average speed of the molecules in the sample?It does not change.
- 26A heat engine takes 2.0 moles of an ideal gas through the reversible cycle abca, on the pV diagram shown in the figure. The path bc is an isothermal process. The temperature at c is 820 K, and the volumes at a and c are 0.010 m3 and 0.16 m3, respectively. The molar heat capacity at constant volume, of the gas, is 37 J/mol∙K, and the ideal gas constant is R = 8.314 J/(mol∙K). What is the thermal efficiency of the engine?Chat gpt
- 27A cat falls from the top of a fence. After it first contacts the ground until it has stopped, the magnitude of the average normal force that the ground exerts on the cat is…greater than the weight of the cat
- 28What forces act on m2. Select all that apply -- may be more than one.m2g (weight of m2)
normal force from the ground
normal force from box m1
- 29A man is pushing a large crate across a rough floor at an increasing speed in one direction. There is a friction force between the crate and the floor. The crate increases in speed because... (hint: some answers may be true but do not explain this, so they are incorrect)the force of the man on the crate is greater than the force of friction on the crate.
- 30A truck, starting from rest, accelerates to the right. A large box sits in the back of the truck and moves with the truck. What type of friction force, and in what direction, acts on the box from the bed of the truck?Static friction to the right
- 31Columbus resident Conn Baker popularized the bicycle loop trick as a circus act around 1905 (he’s the one in the picture). At the peak of the loop, as depicted in the picture, what is the direction of the net force on the bike and rider? Ignore friction and air resistance.down
- 32A refrigerator with a weight of 500 N sits on a floor. The coefficient of kinetic friction is 0.40 and the coefficient of static friction is 0.50. A force of 100 N is applied horizontally to the refrigerator. What is the magnitude of the friction force on the refrigerator? (Hint: does the refrigerator move?)100 N
- 33A soccer player kicks a ball as it sits on the ground. The ball’s initial velocity after the kick is 37 m/s at an angle of 38° above horizontal. What is the maximum height of the ball above the ground?26 m
- 34Two boxes are tied by a massless frictionless rope (dashed line) over a massless frictionless pulley. The large box is already moving down the ramp due to forces that were but are no longer applied. The coefficient of kinetic friction between the box and the surface is 0.47. What is the acceleration of the small box? Show all appropriate steps and make your directions clear.Chat gpt
- 35An amusement park has a ride that is a 4.3 m radius rotor where people stand against the wall, the ride spins, then the floor drops out and friction holds the people up. The amusement park operator wants to make it more thrilling by tilting the walls in by 17° (from vertical). He thinks that he can rotate the ride so that the people are moving at 11 m/s. What coefficient of friction must he have between the people and the wall so that the people avoid falling? Hint: what is the direction of the acceleration?Chat gpt
- 36Two men, Joel and Jerry, push against an unmoving wall. Jerry stops after 10 min, while Joel is able to push for 5.0 min longer. Compare the work they do.Neither of them does any work.
- 37A 4.0-kg object is moving with speed 2.0 m/s. A 1.0-kg object is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greater distance before stopping?Both objects travel the same distance.
- 38Is it possible for a system to have negative potential energy?Yes, since the choice of the zero of potential energy is arbitrary.
- 39Block 1 and block 2 have the same mass, m, and are released from the top of two inclined planes of the same height making 30° and 60° angles with the horizontal direction, respectively. (I.e. block 1 is on the 30° slide.) If the coefficient of friction is the same in both cases, which of the blocks is going faster when it reaches the bottom of its respective incline?Block 2 is faster.
- 40A small glider is coasting horizontally when suddenly a very heavy piece of cargo falls out of the bottom of the plane. You can neglect air resistance. Just after the cargo has fallen outneither the cargo nor the plane change speed.
- 41In a collision between two objects having unequal masses, how does magnitude of the impulse imparted to the lighter object by the heavier one compare with the magnitude of the impulse imparted to the heavier object by the lighter one?Both objects receive the same impulse.
- 42A dumbbell-shaped object is composed by two equal masses, m, connected by a rod of negligible mass and length r. If M1 is the moment of inertia of this object with respect to an axis passing through the center of the rod and perpendicular to it and M2 is the moment of inertia with respect to an axis passing through one of the masses, it follows thatM2 >M1.
- 43A metal bar is hanging vertically from a hook in the ceiling when it is suddenly struck by a ball that is moving horizontally (see figure). The ball is covered with glue, so it sticks to the bar. During this collisionthe angular momentum of the system (ball and bar) is conserved about the hook because neither the hook nor gravity exerts any torque on this system about the hook.
- 44A heavy boy and a lightweight girl are balanced on a massless seesaw. If they both move forward so that they are one-half their original distance from the pivot point, what will happen to the seesaw? Assume that both people are small enough compared to the length of the seesaw to be thought of as point masses.Nothing will happen; the seesaw will still be balanced.
- 45A solid sphere, a solid cylinder, and a hollow pipe all have equal masses and radii and are of uniform density. If the three are released simultaneously at the top of an inclined plane and roll without slipping, which one will reach the bottom first?solid sphere
- 46A 3.45-kg centrifuge takes 100 s to spin up from rest to its final angular speed with constant angular acceleration. A point located 8.00 cm from the axis of rotation of the centrifuge moves with a speed of 150 m/s when the centrifuge is at full speed. (a) What is the angular acceleration (in rad/s2) of the centrifuge as it spins up? (b) How many revolutions does the centrifuge make as it goes from rest to its final angular speed?Chat gpt
- 47A 15-g bullet is shot vertically into an 2-kg block. The block lifts upward 8.0 mm (see the figure). The bullet penetrates the block and comes to rest in it in a time interval of 0.0010 s. Assume the force on the bullet is constant during penetration and that air resistance is negligible. Find the initial kinetic energy of the bullet (the kinetic energy of the bullet just before it hits the block).Chat gpt
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- Fichas sobre Sin título, creado por Linh D. el 30/07/2023.
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- Linh D.
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