Physics Final

1. A 7.0-kg bowling ball experiences a net force of 5.0 N. What will be its acceleration?

(0.71 m/s2)

39. A plane is moving due north- directly towards its destination. Its airspeed is 200 mph. A constant breeze is blowing from west to east at 30 mph. At what rate is the plane moving north?

(198 mph)

21. A hiker walks 200 m west and then walks 100 m north. In what direction is her resulting displacement?

(26.6 N of W)

6. A European sports car dealer claims that his car will accelerate at a constant rate from rest to 100 km/hr in 8.00 s. If sowhat is the acceleration?

(3.47 m/s2 )

20. Doug hits a hockey puck, giving it an initial velocity of 6.0 m/s. If the coefficient of kinetic friction between ice and puck is 0.050, how far will the puck slide before stopping?

(37 m)

35. A stone is thrown with an initial speed of 15 m/s at an angle of 53 above the horizontal from the top of a 35 m building. If g = 9.8 m/s2 and air resistance is negligible- what is the magnitude of the horizontal displacement of the rock?

(38 m)

2. An object moves 20 m east in 30 s and then returns to its starting point taking an additional 50 s. If west is chosen as the positive direction what is the sign associated with the average velocity of the object?

(0, no sign)

18. A baseball is released at rest from the top of the Washington Monument. It hits the ground after falling for 6.0 s. What was the height from which the ball was dropped? Ignore air resistance.

(1.8 x 102 m)

31. A stone is thrown at an angle of 30 above the horizontal from the top edge of a cliff with an initial speed of 12 m/s. A stop watch measures the stone's trajectory time from top of cliff to bottom to be 5.6 s. What is the height of the cliff? Ignore air resistance.

(120 m)

20. Human reaction time is usually about 0.20 s. If your lab partner holds a ruler between your finger and thumb and releases it without warning how far can you expect the ruler to fall before you catch it?

(20 cm)

16. A rock is thrown straight up with an initial velocity of 24.5 m/s.What maximum height will the rock reach before starting to fall downward? Take acceleration due to gravity as 9.80 m/s2 .

(30.6 m)

9. A boxcar of mass 200 tons at rest becomes uncoupled on a 2.5 grade. If the track is considered to be frictionless- what speed does the boxcar have after 10 seconds?

(4.3 m/s)

14. A 500-N tightrope walker stands at the center of the rope. If the rope can withstand a tension of 1 800 N without breaking- what is the minimum angle the rope can make with the horizontal?

(8 degrees)

11. A ball is pushed with an initial velocity of 4.0 m/s. The ball rolls down a hill with a constant acceleration of 1.6 m/s2 . The ball reaches the bottom of the hill in 8.0 s. What is the ball's velocity at the bottom of the hill?

(17 m/s)

4. A 2 000-kg sailboat experiences an eastward force of 3 000 N by the ocean tide and a wind force against its sails with magnitude of 6 000 N directed toward the northwest (45 N of W). What is the magnitude of the resultant acceleration?

(2.2 m/s^2)

15. A Cessna aircraft has a lift-off speed of 120 km/hr. What minimum constant acceleration does this require if the aircraft is to be airborne after a take-off run of 240 m?

(2.31 m/s2 )

13. When a drag strip vehicle reaches a velocity of 60 m/s it begins a negative acceleration by releasing a drag chute and applying its brakes. While reducing its velocity back to zero, its acceleration along a straight line path is a constant 7.5 m/s2 . What displacement does it undergo during this deceleration period?

(240 m)

11. A 5 000-N weight is held suspended in equilibrium by two cables. Cable 1 applies a horizontal force to the right of the object and has a tension- T1. Cable 2 applies a force upward and to the left at an angle of 37.0 to the negative x axis and has a tension- T2. What is the tension -T1?

(6 640 N)

3. Two ropes are attached to a 40-kg object. The first rope applies a force of 25 N and the second 40 N. If the two ropes are perpendicular to each other- what is the resultant acceleration of the object?

(1.2 m/s2)

24. A string attached to an airborne kite is maintained at an angle of 40 with the horizontal. If a total of 120 m of string is reeled in while bringing the kite back to the ground what is the horizontal displacement of the kite in the process? Assume the kite string doesn't sag.

(92 m)

6. Two blocks- joined by a string- have masses of 6.0 and 9.0 kg. They rest on a frictionless horizontal surface. A 2nd string attached only to the 9-kg block- has horizontal force = 30 N applied to it. Both blocks accelerate. Find the tension in the string between the blocks.

(12 N)

29. A baseball thrown from the outfield is released from shoulder height at an initial velocity of 29.4 m/s at an initial angle of 30.0 with respect to the horizontal. What is the maximum vertical displacement that the ball reaches during its trajectory?

(11.0 m)

4. A cheetah can run at approximately 100 km/hr and a gazelle at 80.0 km/hr. If both animals are running at full speed with the gazelle 70.0 m ahead, how long before the cheetah catches its prey?

(12.6 s)

21. Three identical 6.0-kg cubes are placed on a horizontal frictionless surface in contact with one another. The cubes are lined up from left to right and a force is applied to the left side of the left cube causing all three cubes to accelerate to the right at 2.0 m/s2 . What is the magnitude of the force exerted on the right cube by the middle cube in this case?

(12N)

10. A 50-g ball traveling at 25.0 m/s is bounced off a brick wall and rebounds at 22.0 m/s. A high-speed camera records this event. If the ball is in contact with the wall for 3.50 ms what is the average acceleration of the ball during this time interval?

(13 400 m/s2 )

16. A block of mass 5.00 kg rests on a horizontal surface where the coefficient of sliding kinetic friction between the two is 0.200. A string attached to the block is pulled horizontally- resulting in a 2.00-m/s2 acceleration by the block. Find the tension in the string.

(19.8 N)

37. A boat moves at 10.0 m/s relative to the water. If the boat is in a river where the current is 2.00 m/s- how long does it take the boat to make a complete round trip of 1 000 m upstream followed by a 1 000-m trip downstream?

(208 s)

22. A sled weighs 100 N. It is held in place on a frictionless 20 slope by a rope attached to a stake at the top; the rope is parallel to the slope. Find the tension in the rope.

(34N)

8. A 15-kg block rests on a level frictionless surface and is attached by a light string to a 5.0-kg hanging mass where the string passes over a massless frictionless pulley. If g = 9.8 m/s2 -what is the tension in the connecting string?

(37 N)

15. A 20-kg traffic light hangs midway on a cable between two poles 40 meters apart. If the sag in the cable is 0.40 meters- what is the tension in each side of the cable?

(4 900 N)

17. A rock is thrown straight up with an initial velocity of 19.6 m/s. What time interval elapses between the rock's being thrown and its return to the original launch point?

(4.00 s)

32. A stone is thrown at an angle of 30 above the horizontal from the top edge of a cliff with an initial speed of 12 m/s. A stop watch measures the stone's trajectory time from top of cliff to bottom to be 5.6 s. How far out from the cliff's edge does the stone travel horizontally? Ignore air resistance.

(58 m)

7. A 10-kg mass and a 2.0-kg mass are connected by a light string over a massless-frictionless pulley. If g = 9.8 m/s2 what is the acceleration of the system when released?

(6.5 m/s2)

36. A jet airliner moving at 500 mph due east moves into a region where the wind is blowing at 120 mph in a direction 30.0 north of east. What is the new velocity and direction of the aircraft?

(607 mph / 5.67 N of E)

23. The following force vectors act on an object: i) 50.0 newtons at 45.0 north of east and ii) 25.0 newtons at 30.0 south of east. What is the magnitude of the resultant force and its angle relative to the easterly direction?

(61.4 newton at 21.8)

5. A railroad train travels forward along a straight track at 80.0 m/s for 1 000 m and then travels at 50.0 m/s for the next 1 000 m. What is the average velocity?

(61.5 m/s)

12. A cart is given an initial velocity of 5.0 m/s and experiences a constant acceleration of 2.0 m/s2 . What is the magnitude of the cart's displacement during the first 6.0 s of its motion?

(66 m)

2. An astronaut applies a force of 500 N to an asteroid and it accelerates at 7.00m/s2. What is the asteroid's mass?

(71 kg)

5. A 2 000-kg sailboat experiences an eastward force of 3 000 N by the ocean tide and a wind force against its sails with magnitude of 6 000 N directed toward the northwest (45 N of W). What is the direction of the resultant acceleration?

(74 N of W)

27. John throws a baseball from the outfield from shoulder height- at an initial velocity of 29.4 m/s at an initial angle of 30.0 with respect to the horizontal. The ball is in its trajectory for a total interval of 3.00 s before the third baseman catches it. Ignore the air resistance. What is the ball's horizontal displacement?

(76.4 m)

12. A 5 000-N weight is suspended in equilibrium by two cables. Cable 1 applies a horizontal force to the right of the object and has a tension- T1. Cable 2 applies a force upward and to the left at an angle of 37.0 to the negative x axis and has a tension- T2. Find T2.

(8 310 N)

22. A taxicab moves five blocks due north five blocks due east and another two blocks due north. Assume all blocks are of equal size. What is the magnitude of the taxi's displacement start to finish?

(8.6 blocks)

14. A drag racer starts from rest and accelerates at 10 m/s2 for the entire distance of 400 m (1/4 mile). What is the velocity of the race car at the end of the run?

(89 m/s)

38. A river flows due east at 3.0 m/s. A boat crosses the 300-m-wide river by maintaining a constant velocity of 10 m/s due north relative to the water. If no correction is made for the current- how far downstream does the boat move by the time it reaches the far shore?

(90 m)

23. A sled weighs 100 N. It is held in place on a frictionless 20 slope by a rope attached to a stake at the top; the rope is parallel to the slope. What is the normal force of the slope acting on the sled?

(94 N)

25. Jack pulls a sled across a level field by exerting a force of 110 N at an angle of 30 with the ground. What are the parallel and perpendicular components-respectively- of this force with respect to the ground?

(95 N/ 55 N)

9. The value of an object's acceleration may be characterized in equivalent words by what?

(rate of change of velocity)

1. Which one temperature, velocity, acceleration, or displacement, is not a vector quantity?

(temperature)

8. A v vs. t graph is drawn for a ball moving in one direction. The graph starts at the origin and at t = 5 s the acceleration of the ball is zero. What is the velocity of the ball at t = 5 s?

(the velocity of the ball is not changing)

28. A baseball thrown from the outfield is released from shoulder height at an initial velocity of 29.4 m/s at an initial angle of 30.0 with respect to the horizontal. If it is in its trajectory for a total of 3.00 s before being caught by the third baseman-what is the ball's net vertical displacement during its 3-s trajectory?

(zero)

7. A European sports car dealer claims that his product will accelerate at a constant rate from rest to a speed of 100 km/hr in 8.00 s. What is the speed after the first 5.00 s of acceleration?

(17.4 m/s)

40. Alex- parked by the side of an east-west road- is watching car P- which is moving in a westerly direction. Barbara- driving east at a speed 52 km/h- watches the same car. Take the easterly direction as positive. If Alex measures a speed of 78 km/h for car P- what velocity will Barbara measure?

(-130 km/h)

19. A 100-kg box is placed on a ramp. As one end of the ramp is raised, the box begins to move downward just as the angle of inclination reaches 15. What is the coefficient of static friction between box and ramp?

(0.27)

17. A horizontal force of 750 N is needed to overcome the force of static friction between a level floor and a 250-kg crate. If g = 9.8 m/s2 , what is the coefficient of static friction?

(0.31)

3. An object moves 20 m east in 30 s and then returns to its starting point taking an additional 50 s. If west is chosen as the positive direction what is the average speed of the object?

(0.50 m/s)

13. A 500-N tightrope walker stands at the center of the rope such that each half of the rope makes an angle of 10.0 with the horizontal. What is the tension in the rope?

(1 440 N)

18. A horizontal force of 750 N is needed to overcome the force of static friction between a level floor and a 250-kg crate. What is the acceleration of the crate if the 750-N force is maintained after the crate begins to move and the coefficient of kinetic friction is 0.12?

(1.8 m/s2 )

26. A jogger runs halfway around a circular path with a radius of 60 m. What-respectively-are the magnitude of the displacement and the distance jogged?

(120 m / 188 m)

30. A baseball is thrown by the center fielder (from shoulder level) to home plate where it is caught (on the fly at an equal shoulder level) by the catcher. At what point is the ball's speed at a minimum? Ignore air resistance.

(at the top of the trajectory)

19. A rock released at rest from the top of a tower hits the ground after 1.5 s. What is the speed of the rock as it hits the ground? Ignore air resistance.

(15 m/s)

34. A stone is thrown with an initial speed of 15 m/s at an angle of 53 above the horizontal from the top of a 35 m building. If g = 9.8 m/s2 and air resistance is negligible- then what is the speed of the rock as it hits the ground?

(30 m/s)

10. As a 3.0-kg bucket is being lowered into a 10-m-deep well- starting from the top the tension in the rope is 9.8 N. What is the acceleration of the bucket?

(6.5 m/s2 downward)

33. A stone is thrown with an initial speed of 15 m/s at an angle of 53 above the horizontal from the top of a 35 m building. If g = 9.8 m/s2 and air resistance is negligible

then what is the magnitude of the vertical velocity component of the rock as it hits the ground?, (29 m/s)