Physics Honors Final
Which of the following could NOT be a resultant of a 3 m vector and a 4 m vector? a) 7 m b) 1 m c) 0 m d) 3.6 m
0 m
If I weigh 648 N on Eath and 5320 N on the surface of a nearby planet, which is the acceleration due to gravity on that planet? a) 80.5 m/s^2 b) 92.6 m/s^2 c) 70.0 m/s^2 d) 58.8 m/s^2
1) 80.5 m/s^2 Fg = ma 648 = m(9.8) m = 66.1 kg 5320 = 66.1 (a) a = 80.45 m/s^2
Complete the following statement. Today the standard meter is defined in terms of a) a platinum iridium bar kept in France b) the speed of light c) the wavelength of light given off by a krypton atom
B) the speed of light
Given the graph below, what would be the force at 9 meters? [graph with line that goes past 3,6,9,12,15,18,21] a) 5.0 N b) 6.0 N c) 6.5 N d) 7.5 N
C) 6.5 N
Car A uses tires with coefficient of static friction 1.1 with the road on an unbanked curve. The maximum speed at which car A can go around this curve is 25 m/s. Car B has tires with friction coefficient of 0.85. What is the maximum speed at which car B can negotiate the curve?
Car A ------- mv^2 OVER r = umg cancel out m v^2 = ugr 25^2 = 1.1(9.8) r r = 58 m Car B -------- v = square root of ugr v = square root of 0.85(9.8)(58) v = 22.98 m/s
A plane has a speed of 800 km/hr north with respect to the air. If it encounters a wind speed of 100 km/hr at 30 degrees.
Vpa = 800 Vag = 30 Vpg = Vpa + Vag horizontal ---------- 0 100cos30 --------- - 86.6 vertical ---------- 800 -100sin30 ----------- 750 86.6^2 + 750^2 = R^2 R = 755 km/hr tan-1 (750 OVER 86.6) = 88.1 degrees NW
Under the action of a constant force an object accelerates at 7.8 m/s^2. What will the acceleration be if a) the force is halved? b) the object's mass if halved? c) the force and the other object's mass are both halved? d) the force is halved and the object's mass is doubled? a) 3.9 m/s^2, 16 m/s^2, 7.8 m/s^s, 7.8 m/s^2 b) 3.9 m/s^2, 16 m/s^2, 7.8 m/s^s, 7.8 m/s^2 c) 16 m/s^2, 3.9 m/s^2, 2.0 m/s^2, 7.8 m/s^2 d) 3.9 m/s^2, 16 m/s^2, 2.0 m/s^2, 7.8 m/s^2
a or b) 3.9 m/s^2, 16 m/s^2, 7.8 m/s^s, 7.8 m/s^2
A speedometer on your car measures your speed with a 3% uncertainty. a) what range of speeds are you traveling if the speedometer reads 60 km/hour. b) Are you traveling faster or slower than a cheetah running at 25 m/s. Defend your answer with calculations.
a) 0.03 x 60 = 1.8 km/hr 58.2 km/hr - 61.8 km/hr b) 60 km | 1000 m | 1 hour ------------------------- 1 hr | 1 km | 3600 seconds = 16.67 m/s slower
Look at the diagram below, which arrow represents the direction of the centripetal acceleration at the location of the space ship? [picture of a crayon-like rocket ship orbiting an earth-like blob with dotted circle outline, and a list of arrows a) 1 [---->] b) 5 [arrow pointing diagonal right down] c) 4 [arrow pointing down] d) 3 [^] e) 2 [<----]
a) 1 [---->]
If a man is swimming 5 m/s across a river that has a current of 2 m/s, which velocity will determine how far downriver he will end up? a) 2 m/s b) 5 m/s c) the average of the two velocity d) the resultant of the two velocities
a) 2 m/s
A ball is thrown with an initial velocity of 30 m/s and an initial vertical velocity of 20 m/s. At the top of the flight trajectory, the horizontal velocity is a) 30 m/s b) 0 m/s c) 9.8 m/s d) 20 m/s
a) 30 m/s
An inclined plane makes an angle of 10 degrees with the horizontal. What force is required to cause a 16 kg box to slide up the plane with an acceleration of 2 m/s^2 if the coefficient of friction is 0.1? a) 74.7 N b) 15.2 N c) 132 N d) 25.3 N
a) 74.7 draw a freebody diagram of a ramp with the angle of 10 and a box on top. Fg// points down. Ff points down. Fpush goes up. Fg points down. Fn points up. Fpush - Fg// - Ff = Fnet Fpush - 16(9.8)sin10 - 0.1(16)(9.8)cos10 = 16(2) Fpush = 74.7 N
A satellite having orbital speed V orbits a planet of mass M. If the planet had half as much mass, the orbital speed of the satellite would be: a) V / √ 2 b) V c) v √ 2 d) 2V e) V/2
a) V / √ 2
A person drops one rock form rest and it falls 100 meters down a cliff before hitting the ground. The person then throws an identical rock downward. The amount of kinetic energy gained by the rock dropped from rest is _______ that of the second rock, and the magnitude of the change in speed (between hitting the ground and its initial speed) of the rock dropped from rest is ______ that of the second rock. a) equal to, equal to b) equal to, less than c) less than, less than d) equal to, greater than
a) equal to, equal to
A bicyclist is riding at a constant speed along a straight-line path. The rider throws a ball straight up to a height a few meters above her head. Ignoring air resistance, where will the ball land? a) in her hand b) in front of her c) this cannot be answered without knowing the speed of the bicycle and the height it was thrown d) behind her
a) in her hand
A person ties a rock to a string and whirls it around in a vertical circle such that sometimes the rock is going straight upward and sometimes the rock is going straight down. She whirls the rock at the minimum speed (constant in time) such that the string is always taut (no sag). When is the tension the highest? a) it is highest when the rock is at the lowest elevation b) the tension is constant c) it is highest when the rock is at the highest elevation
a) it is highest when the rock is at the lowest elevation
Which one of the following is an SI base? a) kilogram b) gram c) centimeter d) newton
a) kilogram
Which one of the following has the largest kinetic energy? a) the earth moving in its orbit around the sun b) a jet airplane flying at its maximum speed c) a raindrop falling d) a woman swimming
a) the earth moving in its orbit around the sun
If you stood on a planet having a mass four times higher than Earth's mass, and a radius two times longer than Earth's radius, you would weigh a) the same as you do on Earth b) two times more than you do on Earth c) four times more than you do on earth d) two times less than you do on earth
a) the same as you do on earth
A bullet is aimed at a target on a wall a distance L away from the firing position. Because of gravity, the bullet strikes the wall a distance change in y below the mark as suggested in the figure. Note: the drawing is not scale. If the distance L were half as large, and the bullet had the same initial velocity, how would change in y by affected? [drawing of bullet hitting grid wall] a) the vertical displacement would be 1/4 as much b) the vertical displacement would double c) the vertical displacement would be 1/2 as much d) the vertical displacement would be 4 times greater
a) the vertical displacement would be 1/4 as much
A person stands on the edge of a cliff. She throws three identical rocks with the same speed. Rock X is thrown vertically upward, rock Y is thrown horizontally, and rock Z is thrown vertically downward. Assuming the elevation loss of the three rocks is the same (the base of the cliff is flat), which rock hits the ground with the highest speed? a) they all hit the ground at the same time b) Rock X c) Rock Y d) Rock Z
a) they all hit the ground at the same time
If you were to move into outer space far from any stars or planets, a) your weight would change, but your mass would not change b) you mass would change, but your weight would not change c) neither your weight nor your mass would change d) both your weight and mass would change e) none of these is true
a) your weight would change, but your mass would not change
Which of the following is a reasonable measurement for the height of a person? a) 10m b) 1.8 m c) 0.5 m d) 5.6m
b) 1.8 m
Two cars approach each other on a straight and level road. Car A is traveling at 75 km/h, due north, and car B is traveling at 45 km/h, due south. Both velocities are measured in relative to ground. What is the velocity of car A relative to an observer in car B? a) 75 km/h, north b) 120 km/h, north c) 30 km/h south d) 30 km/h, north
b) 120 km/h, north
The figure shows two forces of equal magnitude acting on an object. If the common magnitude of the forces is 7.7 N and the angle between them is 40 degrees, what third force will cause the object to be in equilibrium? [arrow angle opening to the left labeled F1 and F2] a) 7.2 N pointing to the right b) 14.5 N pointing to the right c) 12.5 N pointing to the right d) 5.9 N pointing to the right
b) 14.5 pointing to the right label inside of the arrows with 20 degrees on top and 40 degrees on bottom, then a line extending in opposite direction from the core with f ? 7.7 cos 20 + 7.7 cos 20 = F F = 14.47 N
A 1000 kg car experiences a net force of 9500 N while decelerating from 30 m/s to 23.4 m/s. How far does it travel while slowing down? a) 17 m b) 19 m c) 20 m d) 22 m
b) 19 m KE - W = KE 1/2mv^2 - f x d = 1/2mv^2 1/2(1000)(30^2) - 9500 x d = 1/2(1000)(23.4)^2 d = 18.5 m
Joan hits the tennis ball horizontally from 2.5 m above the ground at the velocity of 32 m/s. How far will the ball travel before it strikes the ground? a) 22.85 m b) 22.7 m c) 33.7 m d) 29.6 m
b) 22.7 m draw a person holding a tennis racket - label the 32 m/s above and the 2.5 m below then do horizontal and vertical chart. horizontal ----------- vi = 32 x = t = 0.714 vertical ---------- vi = 0 x = 2.5 m t = a = 9.8 vfy = x = 1/2at^2 2.5 = 1/2(9.8)t^2 t = 0.714 d= rt d = 32(0.714) = 22.9
the gravitational potential energy of a box sliding down an inclined plane decreases by 25 J while the kinetic energy increases by 23 J. Which of the following best describes the scenario? a) the law of conservation of energy is violated in this situation b) 2J of energy is transferred to thermal energy c) the total kinetic energy of the system must remain at 48 .J d) the kinetic energy of the box must be 25 J
b) 2J of energy is transferred to thermal energy
A person with a mass of 51 kg is riding in an elevator that is accelerating upward at 1.80 m/s^2. What is the person's apparent weight? a) 410 N b) 590 N c) 500 N d) 630 N
b) 590 N draw freebody diagram with man in a box and 1.8 m/s^2 pointing up. Fg points down. Fn points up. Fn - Fg = Fnet Fn - 51(9.8) = 51 (1.8) Fn = 591.6
A proton moving at 0.999 of the speed of light (3 x 10^8 m/s) orbits a black hole 4972 km from the center of the attractor. What is the mass of the black hole? a) 6.71 x 10^36 kg b) 6.71 x 10^33 kg c) 6.71 x 10^25 kg d) 6.71 x 10^30 kg
b) 6.71 x 10^33 kg v= gm over r all squarerooted 0.999 (3x10^8 m/s) = the square root of 6.67 x 10^ -11 M OVER 4972000 meters M = 6.69 x 10^33 kg
Peter niced a bug crawling along a meter stick and decided to record the bug's position in 5 second intervals. After the bug crawled off the meter stick, Peter created the table shown: [table labeled with Time (s) and position (cm), data reads 0 -20 on time half and 49.6 to 65.7 on the position half] What is the placement if the bug between t = 0 and t = 15? a) 41.0 cm b) 8.6 cm c) 10.5 cm d) 39.2 cm
b) 8.6 cm
For which one of the following situations will the path length equal the magnitude of displacement? a) a ball rises and falls after being thrown straight up from the earth's surface. b) a ball is rolling down an inclined plane c) a train travels 5 miles east: it stops and then travels 2 miles west d) a jogger is running around a circular path
b) a ball is rolling down an inclined plane
In which of the following situations is zero net work done? a) a physics student stretches a spring b) a box is pulled across a rough floor at constant velocity c) a ball rolls down an inclined plane d) a projectile falls toward the surface of Earth
b) a box is pulled across a rough floor at constant velocity
If mass were graphed on the y axis and volume were graphed on the x axis, the resulting slope would have the same units as a) speed b) density c) acceleration d) not enough info
b) density
Given the following graph, what would be the independent variable? [graph with position in y and time on x] a) position b) time c) speed d) slope
b) time
Consider what happens when you jump up in the air. Which of the following is the most accurate statement? a) it is the upward force exerted by the ground that pushes you up, but this force can never exceed your weight. b) when you push down on the earth with a force greater than your weight, the earth pushes back with a force of the same magnitude and thus propels you into the air. c) you are able to spring up because the earth exerts a force upward on you which is stronger than the downward force you exert upon the earth d) since the ground is stationary, it cannot exert the upward force necessary to propel you into the air. Instead, it is the internal forces of your muscles acting on your body itself
b) when you push down on the earth with a force greater than your weight, the earth pushes back with a force of the same magnitude and thus propels you into the air.
If you run around a lake that has a diameter of 2km in 45 minutes, what is your average speed in m/s? [free response]
c = 2pi(1000m) = 6283 m 45 minutes | 60 seconds -------------------------- | 1 minute = 2700 seconds radius = 1 km speed = 6283 ------- 2700 seconds = 2.32 m/s
A sports car can go from rest to 35 m/s in 3.86 s. The same car can come to a full stop from that speed in 12.17 s. What is the ratio of starting to stopping accelerations (starting acceleration/stopping acceleration).? a) -0.32 b) 0.32 c) -3.2 d) 3.2
c) -3.2 Vi = 0 Vf = 35 a = t = 3.86 sec and Vi = 35 vf = 0 a = t = 12.17 sec 35 = 0 + a (3.86) a = 9.07 m/s^s 0 = 35 + a(12.17) a = -2.88 m/s^s 9.07 OVER -2.88 = -3.15
In the diagram below, during which time interval does the object have the highest speed? [position time graph that goes up then down, looks like a jump rope] a) 5 to 10 sec b) 25 to 30 sec c) 0 to 5 sec d) 10 to 20
c) 0 to 5 sec
If a particle has a mass of 1 mg, what's its mass in grams? a) 100 g b) 0.01 g c) 0.001 g d) 1000 g
c) 0.001 g
A car is traveling at an unknown velocity. It accelerates constantly over 5.0 sec at a rate of 3.0 m/s^2 to reach a velocity of 30 m/s. What was the original velocity of the car? a) 20 m/s b) 1.0 m/s c) 15 m/s d) 10 m/s e) 5.0 m/s
c) 15 m/s Vi= ? Vf = 30 m/s a = 3 m/s^2 t = 5 sec Vf = Vi + at 30 = Vi + 3(5) Vi= 15
What would be the most correct measurement for the situation below: [ruler with bar out a little past two cm] a) 2.3 cm b) 2.4 cm c) 2.32 cm d) 2.38 cm
c) 2.32 cm
A helicopter (m = 1250 kg) is cruising at a speed of 25.0 m/s at an altitude of 200 m. What is the total mechanical energy of the helicopter? a) 2.27 x 10^6 c) 6.18 x 10^5 c) 2.84 x 10^6 J d) 3.91 x 10^5 J
c) 2.84 x 10^6 J KE + GPE = Total 1/2(1250)(25)^2 + 1250(9.8)(200) = 2840625
[diagram of weird arrows extending from sun-like ball] For the diagram above, what is the magnitude and direction of the resultant vector? SHOW WORK FOR BOTH THE MAGNITUDE AND THE ANGLE a) 20.6 N at 88.3 degrees up and right b) 35 N straight up c) 20.6 N at 88.3 degrees up and left d) 29 N at 1.7 degrees up and left
c) 20.6 N at 88.3 degrees up and left x ------ -15cos(45) 0 10 --------- -0.61 y ------- 15sin(45) 10 0 -------- 20.6 20.6^2 + 0.61^2 = R^2 r=20.61 tan-1 (20.6 OVER 0.61) = 88.3 degrees
Joe and Bill are playing tug-of-war. Joe is pulling with a force of 200 N. Bill is simply hanging on to the rope. Neither person is moving. What is the tension of the rope? a) 400 N b) 300 N c) 200 N d) 0 N
c) 200 N
In an amusement park ride, passengers stand inside an 8 m radius cylinder. Initially, the cylinder rotates with its axis oriented along the vertical. After the cylinder has acquired sufficient speed, it tilts into a vertical plane, that is, the axis tilts into the horizontal, as shown in the figure. Suppose that, once that axis has tilted into the horizontal, the ring rotates once every 4.5 s. If a rider's mass is 40 kg, with how much force does the ring push on her at the top of the ride? [diagram of ferris wheel looking ride] a) 1000 N b) 620 N c) 230 N d) 390 N
c) 230 N Fc = Fg + Fn mv^2 OVER r = mg + Fn 40(11.17)^2 OVER 8 = 40 (9.8) + Fn Fn = 231.9 N
Future space stations will create artificial gravity by rotating. Consider a cylindrical space station of 380 m diameter rotating about its axis. Astronauts walk on the inside surface of the space station. What rotation period will provide normal gravity? a) 4.4 s b) 39 s c) 28 s d) 6.2 s
c) 28 s
The wavelength of a certain laser is 0.66 micrometers. What is the wavelength in nanometers? [free response with mc] a) 6.6 x 10^3 nm b) 6.6 x 10^4 nm c) 6.6 x 10^2 nm d) 6.6 x 10^1 nm
c) 6.6 x 10^2 nm 0.66 um | 10^-6 m | 1 nm -------------------------- | 1 um | 10^ -9 m
A 0.18 m radius pulley is free to rotate about a horizontal axis. A 4.2 kg mass and a 8.0 kg mass are attached by massless string, which is hung over the pulley. If the string does not slip, calculate the magnitude of the net torque on the pulley about its rotational axis. [circle with strings and two blocks labeled m1 and m2 pulling down on either side. sort of looks like a doorknob with some homemade doorknocker slipping around it] a) 5.5 N x m b) 7.6 N x m c) 6.7 N x m d) 9.5 N x m
c) 6.7 N x m LABEL the mass blocks: m1 = 4.2 kg and m2 = 8 kg also label the torques Tccw on the left pointing down and Tcw on the right pointing down Tnet = Tcw - Tccw Tnet = 8(9.8)(.18)-(4.2)(9.8)(.18) Tnet = 6.7 N x m
A hobby rocket reaches a height of 55.2 m and lands 92 m from the launch point. What was the angle of launch? a) 42.5 degrees b) 75.2 degrees c) 67.4 degrees d) 45 degrees
c) 67.4 degrees horizontal ---------- vi = vcosthata x = 92 t = 6.71 sec vertical --------- vi = vsinthata x = 55.2 t = vf = 0 a = -9.8 92 = vi(6.71) vix = 13.7 m/s 0 = viy^2 + 2(-9.8)(55.2) vi = 32.9 m/s tan-1 (32.9 OVER 13.7) = 67.4 degrees
A package is dropped from a helicopter moving upward at 15 m/s. If it takes 14.0 s before the package strikes the ground, how high above the ground was the package when it was released? (Disregard air resistance) a) 1200 m b) 900 m c) 750 m d) 600 m
c) 750 m Vi = 15 m/s vf a = -9.8 m/s^s x = ? t = 14 sec x=1/2at^2 + ViT x = 1/2(-9.8)(14)^2 + (15) (14) x = -750.4 m
You walk 55 m to the east, then turn 60 degrees to your right and walk another 45 m. How far are you from where you originally started? SHOW YOUR ANSWER BOTH GRAPHICALLY AND ALGEBRAICALLY a) 46 m b) 94 m c) 87 m d) 50 m
c) 87 m draw a triangle - label 55 m on the left side and 45 on the lower right and angle of 60 coming out of the top (R across hypotenuse) x ------ 55 45 cos 60 ------- 77.5 y ------- 0 45sin60 --------- 39 77.5^2 + 39^2 = R^2 R = 86.7
A block slides up an inclined plane. Which of the following expressions describes the net force equation on the block? a) Fnet = Fg b) Fnet = Fg// c) Fnet = Fg// + Ff d) Fnet = Fg// - Ff
c) Fnet = Fg// + Ff
The plot below shows the position of an object as a function of time. The letters H-L represent particular moments of time. At which moment in time is the speed of the object equal to zero? [position time graph that looks like a sand dune] a) L b) K c) I e) H e) J
c) I
a women is straining to lift a large crate, without success. It is too heavy. We denote the forces on the crate as follows: P is the upward force being exerted on the crate by the person, C is the contact force on the crate by the floor, and W is the weight of the crate. [diagram of weird woman trying to lift crate] How are the magnitudes of these forces related, while the person is trying unsuccessfully to lift the crate? a) P + C > W b) P = C c) P + C = W d) P + C < W
c) P + C = W
In which of the following systems is there a decrease in gravitational potential energy? a) a crate rests at the bottom of an inclined plane b) a car ascends a steep hill c) a girl jumps down from a bed d) a boy stretches a horizontal spring
c) a girl jumps down from a bed
When multiplying measurements, how can you find the overall uncertainty? a) multiply the uncertainties of the measurements b) find the percent uncertainty of each measurement then multiply the percent uncertainties and use these to find the overall uncertainty c) find the percent uncertainty of each measurement then add the percent uncertainties and use these to find the overall uncertainty d) add uncertainties of the measurements
c) find the percent uncertainty of each measurement then add the percent uncertainties and use these to find the overall uncertainty
A racecar is traveling at constant speed around a circular track. What happens to the centripetal acceleration of the car if the speed is doubled? a) It increased by a factor of 2 b) it is decreased by a factor of 1/2 c) it increase by a factor of 4 d) it remains the same
c) it increased by a factor of 4
Which one of the following statements most accurately describes the center of gravity of an object? a) it is the point where gravity acts on the object b) it is the point on the object where all the weight is concentrated c) it is the point from which the torque produced by the weight of the object can be calculated d) it is the point where all the mass is concentrated
c) it is the point from which the torque produced by the weight of the object can be calculated
Two identical stones are dropped from a taller building, one after the other meaning, one is dropped then a second later the second one is dropped. Assume air resistance is negligible. While both stones are falling, what will happen to the vertical distance between them? a) it will remain the same b) it will decrease c) it will increase d) it will first increase and then remain constant
c) it will increase
which one of the following is an example of a non-conservative force? a) electrical force b) elastic spring force c) kinetic frictional force d) gravitational force
c) kinetic frictional force
A large truck collides head-on with a cyclist. During the collision. a) the truck exerts a force on the cyclist, but the cyclist exerts no force on the truck b) the truck exerts a smaller amount of force on the cyclist than the cyclist exerts on the truck c) the truck exerts the same amount of force on the cyclist as the cyclist exerts on the truck d) the truck exerts a greater amount of force on the cyclist than the cyclist exerts on the truck
c) the truck exerts the same amount of force on the cyclist as the cyclist exerts on the truck
While in flight, how do the x and y components of the velocity vector of the ball compare at the points B and C? [diagram of half parabola extending off a platform and points a, b, c, and d] a) the x component is larger at C than at B; the y component at B points up while at C, it points downward b) the velocity components are non-zero at B and zero at C c) the x components are the same; the y component has a larger magnitude at C than at B d) the x components are the same; the y component at C is zero m/s
c) the x components are the same; the y component has a larger magnitude at C than at B
A block of mass is released from rest at a height R above a horizontal surface. The acceleration due to gravity is g. The block slides along the inside of a frictionless circular hoop of radius R. Which one of the following expressions gives the speed of the block at the bottom of the hoop. a) v = mgR b) zero m/s^2 c) v^2 = 2gR d) v = mg/2R
c) v^2 = 2gR
A stalled car is being pushed up a hill by three people, and it is moving at a constant speed. The net force on the car is a) in the same direction of the car's motion b) in the opposite direction of the car's motion c) zero d) none of the above
c) zero
In the diagram below, which time interval does the object have the highest speed? [velocity time graph that looks like tetris grid] a) 5-10 sec b) 25 to 30 sec c) 10 to 20 sec d) 0-5 sec
d) 0-5 sec
11) a weight lifter can bench 171 kg. How many milligrams (mg) is this? [free response with mc] a) 1.71 x 10^9 mg b) 1.71 x 10^6 mg c) 1.71 x 10^7 mg d) 1.71 x 10^8 mg
d) 1.71 x 10^8 mg 171 kg | 10^3 g | 1 mg ---------------------- | 1 kg | 10^ -3 g
A Ferrari accelerates from 0 to 100 km/h in 4.80 s. What force (in Newtons) does a passenger of a mass 50.0 kg experience during acceleration? a) 60.3 N b) 252 N c) 229 N d) 289 N
d) 289 N 100 km/hr = 27.8 m/s a = change in v over t = 27.8 over 4.8 = 5.79m/s^2 F = ma = 50(5.79) = 289 N
An archer pulls a bowstring back a distance of 20 cm with an average force of 75 N. The arrow has a mass of 20 g. When he releases the string, what is the velocity of the arrow when it leaves the bow? a) 1.2 m/s b) 22 m/s c) 32 m/s d) 39 m/s e) 42 m/s
d) 39 m/s^2 convert units. 20 cm = 0.2 m and 20 g = 0.020 kg w = f x d 75 (0.2) = 15 J 15 = 1/2(0.02)v^2 v = 38.7 m/s
An oak tree was planted 22 years ago. How many seconds does this correspond to? (Do not take leap days into account.) [free response with mc] a) 2.8 x 10^8 b) 2.9 x 10^7 c) 1.2 x 10^7 d) 6.9 x 10^8
d) 6.9 x 10^8 22 years | 365 d | 24 hours | 3600 seconds ----------------------------------------------- | y year | 1 day | 1 hour
A traveler pulls on a suitcase at an angle 36 degrees above the horizontal. If 908 J of work are done on the strap while moving the suitcase a horizontal distance of 15 m, what is the tension in the strap? a) 85 N b) 92 N c) 61 N d) 75 N
d) 75 N draw freebody diagram of box with strap pulling up at an angle. mark angle as 36 degrees. w = f x d 908 = f(15) F - 60.53 Fx = Fperpcos36 Fperp = 74.8 N
[velocity time graph titled Car's Velocity vs. Time, looks like a flat top pyramid] Rank the average speeds of the car in regions A, B, C, and E a) A< B > C = E b) B > A = C = E c) A > B > C = E d) B > A = C > E e) E > A = C > B
d) B > A = C = E
A stone is thrown vertically upwards, reaches a highest point, and returns to the ground. When the stone is at the top of its path, its acceleration a) is directed upwards b) changes direction from upwards to downwards c) is zero d) is directed downwards
d) is directed downward
Which one of the following statements concerning kinetic energy is true? a) it can be measured in watts b) it is a quantitative measure of inertia c) it is always equal to the potential energy d) it is always positive
d) it is always positive
A block is at rest on a rough incline as shown [staticky block on a ramp] The frictional force acting on the block, along is incline, is a) greater than the weight of the block b) zero c) equal to the weight of the block d) less than the weight of the block
d) less than the weight of the block
What would you use to find the magnitude of the resultant? [weird triangle diagram with 10 and 20 labeled as the sides] a) tan - 1 x 20 OVER 10 = thata b) sin -1 x 20 OVER 10 = thata c) distance formula d) pythagorean theorem
d) pythagorean theorem
A football is kicked at an angle thata with respect to the horizontal. Which one of the following statements best describes the acceleration of the football during this event if air resistance is neglected? a) the acceleration is 0 m/s^2 when it is at its highest point b) the acceleration starts out as 9.8 m/s^2 and gradually decreases as it reaches its highest point c) the acceleration is 0 m/s^2 at all times d) the acceleration is -9/8 m/s^2 at all times
d) the acceleration is -9/8 m/s^2 at all times
Two bullets are fired simultaneously parallel to a horizontal plane. The bullets have different masses and different initial velocities. Which one will strike the plane first? a) they strike the plane at the same time b) the lightest one c) the slowest one d) the fastest one e) the heaviest one
d) the fastest one
A rock is thrown straight up from the surface of the Earth. Which one of the following describes the energy transformation of the rock as it rises? Neglect air resistance. a) both the potential energy and the potential energy of the rock increase b) the kinetic energy increases and the potential energy decreases c) the total energy of the rock increases d) the kinetic energy decreases and the potential energy increases
d) the kinetic energy decreases and the potential energy increases
A spaceship is in orbit around the earth at an altitude of 12000 miles. Which one of the following statements best explains why astronauts experience "weightlessness"? a) the force of the gravity decreases as the inverse square of the distance from the earth's center b) the centripetal force of the earth on the astronaut is zero Newtons c) the pull of the earth on the spaceship is canceled by the pull of the other planets d) the spaceship is in free fall and its floor cannot press upwards on the astronauts
d) the spaceship is in free fall and its floor cannot press upwards on the astronauts
Starting from rest, a particle confined to move along a straight path is acceleratied at a rate of 4 m/s^s. Which statement accurately describes the motion of the particle? a) the acceleration of the particl increases by 4 m/s^2 b) the particle travels 4 meters during the first second only. c) the particle travels 4 m during each second d) the speed of the particle increases by 4 m/s during each second
d) the speed of the particle increases by 4 m/s during each second
A boy is whirling a stone around his head by means of a string. The string makes one complete revolution every second, and the tension in the string is Ft. The boy then speeds up the stone, keeping the radius of the circle unchanged, so that the string makes two complete revolutions every second. What happens to the tension in the string? a) the tension reduces to one-fourth of its original value b) the tension reduces to half of its original value c) the tension increases to twice its original value d) the tension increases to four times its original value e) the tension is unchanged
d) the tension increases to four times its original value
Which of the following would decrease the percent uncertainty in a time measurement? a) decrease the time interval that you are measuring b) use a stopwatch that measures out to the thousandths place c) use your fingers to stop/start the stopwatch d)use a timing method that does not involve human reaction time
d) use a timing method that does not involve a human reaction time
Suppose you are playing hockey on a new-age ice surface in which there is no friction between the ice and the hockey puck. You wind up and hit the puck as hard as you can. Just after the puck loses contact with your stick, the puck a) will speed up a little, and then slow down b) will speed up a little, and then move at constant speed c) will start to slow down d) will not slow down or speed up
d) will not slow down or speed up
A toy rocket is launched vertically from the ground level (y = 0), at time t = 0.0 s. The rocket engine provides constant upward acceleration during the burn phase. At the instant of engine burnout, the rocket as risen to 69 m and acquired a velocity of 20 m/s. The rocket continues to rise in unpowered flight, reaches maximum height, and falls back to the ground. The maximum height reached by the rocket is closest to: a) 89 m b) 98 m c) 85 m d) 80 m e) 94 m
draw upside down parabola with point labeled vf = 0 at the top, 20 m/s on left side and 69 m vf^2 = vi^2 + 2ax 0 = 20^2 + 2(-9.8)x x = 20.4 m + 69 m = 89.4 m
Looking at the diagram below, which arrow represents the direction the rocket would go if the earth suddenly disappeared? [picture of rocket that looks like a crayon going past earth-like blob] a) 4 [arrow pointing down] b) 1 [ ----> ] c) 2 [<-------] d) 5 [arrow pointing diagonal right-down] e) 3 [^]
e) 3 [^]
A 1000 kg car traveling at 30 m/s skids 10 m before it stops. What is the magnitude of the frictional force on the car? a) 1500 N b) 3000 N c) 4500 N d) 15000 N e) 45000 N
e) 45000 N KE = w 1/2mv^2 = f x d 1/2(1000)(30)^2 = f(10) f = 45000 N
A car moving at a velocity of 20 m/s is behind a truck moving at a constant velocity of 18 m/s. When the car is 50 m behind the front of the truck, the car accelerates uniformly at 1.8 m/s2. The car continues at the same acceleration until it reaches a velocity of 25 m/s, which is the legal speed limit. The car then continues at a constant velocity of 25 m/s, until it passes the front of the truck. The distance the car travels while accelerating, in meters, is closest to: a) 54 b) 58 c) 50 d) 66 e) 62
e) 62 CAR ------ Vi = 20 m/s a = 1.8 vf = 25 m/s vf^2 = vi^2 + 2ax 25^2 = 20^2 + 2(1.8)x x = 62.5 TRUCK --------- vi = 18 m/s
A satellite of mass M takes time T to orbit a planet. If the satellite had twice as much mass, the time for it to orbit the planet would be: a) 2T b) 4T c) T/2 d) T/4 e) T
e) T
[velocity time graph titled Car's Velocity vs Time, looks like a flat-top pyramid] Which of the following best describes the motion of the car in regions C, D, and E of the velocity-time graph above? a) it accelerates at a constant, nonzero acceleration except at point C when its acceleration is zero. b) it moves at a constant velocity in the negative direction c) it position changes at a constant rate e) it is slowing down until it reverses direction and speeds back up again
e) it is slowing down until it reverses direction and speeds back up again
