# Get assignment solution or answer for "During a hard sneeze, your eyes might shut for 0.46 s. If you are driving a car at 95 km/h during such a sneeze, how far..."

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- During a hard sneeze, your eyes might shut for 0.46 s. If you are driving a car at 95 km/h during such a sneeze, how far does the car move during that time?
- The position of an object moving in a straight line is given by
*x*= 4*t*− 3*t*^{2}+ 5*t*^{3}, where*x*is in meters and*t*in seconds.

(a) What is the position of the object at *t* = 1 s? What is the position of the object at *t* = 2 s? What is the position of the object at *t* = 3 s? What is the position of the object at *t* = 4 s?

(b) What is the object's displacement between *t* = 0 s and *t* = 4 s? (Indicate the direction with the sign of your answer.)

(c) What is the average velocity for the time interval from *t* = 2 s to *t* = 4 s? (Indicate the direction with the sign of your answer.)

(d) Graph *x* versus *t* for 0 s ≤ *t* ≤ 4 s and indicate how the answer for (c) can be found on the graph.

3.At a certain time a particle had a speed of 19 m/s in the positive *x* direction, and 2.9 s later its speed was 29 m/s in the opposite direction. What is the average acceleration of the particle during this 2.9 s interval?

4.An electron with initial velocity *v*_{0} = 2.70 **✕** 10^{5} m/s enters a region 1.0 cm long where it is electrically accelerated. It emerges with velocity *v* = 6.70 **✕** 10^{6} m/s. What was its acceleration, assumed constant? (Such a process occurs in old-fashioned television sets.)

5.An electric vehicle starts from rest and accelerates at a rate of 2.6 m/s^{2} in a straight line until it reaches a speed of 25 m/s. The vehicle then slows at a constant rate of 1.0 m/s^{2} until it stops. (a) How much time elapses from start to stop? (b) How far does the vehicle travel from start to stop?

6.Raindrops fall 1715 m from a cloud to the ground. (a) If they were not slowed by air resistance, how fast would the drops be moving when they struck the ground? (b) Would it be safe to walk outside during a rainstorm?

7.The figure below gives the acceleration *a* versus time *t* for a particle moving along an *x* axis. At *t* = −2.0 s, the particle's velocity is −30 m/s. What is its velocity at *t* = 5.0 s?

8.A rock is dropped from a 330 m high cliff. (a) How long does it take to fall the first 165 m? (b) How long does it take to fall the second 165 m?

9.Compute your average velocity in the following two cases. (a) You walk 75.8 m at a speed of 1.22 m/s and then run 75.8 m at a speed of 3.05 m/s along a straight track. (b) You walk for 1.91 min at a speed of 1.22 m/s and then run for 1.91 min at 3.05 m/s along a straight track. (c) Graph *x* versus *t* for part (a) and indicate how the average velocity is found on the graph.

Graph *x* versus *t* for part (b) and indicate how the average velocity is found on the graph.

10. The position function *x*(*t*) of a particle moving along an *x* axis is *x* = 4.2 − 7.7*t*^{2}, with *x* in meters and *t* in seconds. (a) At what time does the particle (momentarily) stop? (b) Where does the particle (momentarily) stop? (c) At what negative time does the particle pass through the origin? (d) At what positive time does the particle pass through the origin? (e) Graph *x* versus *t* for the range −5 s to +5 s.

(f) To shift the curve leftward on the graph, should we include the term −20*t* or the term +20*t* in *x*(*t*)?(g) Does that inclusion increase or decrease the value of *x* at which the particle momentarily stops?

11. If the position of a particle is given by *x* = 33*t* − 9*t*^{3}, where *x* is in meters and *t* is in seconds, answer the following questions. (a) When, if ever, is the particle's velocity zero? (Enter the value of *t* or 'never'.) (b) When is its acceleration *a* zero? (c) When is *a* negative?

(d) When is *a* positive?(e) Graph *x*(*t*), *v*(*t*), and *a*(*t*). (Submit a file with a maximum size of 1 MB.)

12. A muon (an elementary particle) enters a region with a speed of 5.15 **✕** 10^{6} m/s and then is slowed at the rate of 1.45 **✕** 10^{14} m/s^{2}. (a) How far does the muon take to stop? (b) Graph *x* versus *t* for the muon.

Graph *v* versus *t* for the muon.

13. A hoodlum throws a stone vertically downward with an initial speed of 12.2 m/s from the roof of a building, 39.0 m above the ground. (a) How long does it take the stone to reach the ground? (b) What is the speed of the stone at impact?

14 How far does the runner whose velocity-time graph is shown below travel in 12 s?

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