Class Management Help phys 255_001 1-D Kinematics by careermalls
Class Management Help phys 255_001 1-D Kinematics
Queation 1.
Problem 1: A student witnesses a flash of lightning and then t = 5.5 s later the student hears the associated clap of thunder.
Randomized variables: t = 5.5 s
- Part (a): Sound travels at 343 m/s in the air. What distance from the student is the lightning strike, in meters?
Sound travels at 343 m/s in the air. What distance from the student is the lightning strike, in meters?
- Part (b): Light travels at 3.0 × 108 m/s in the air. How long, t1, in seconds did it take the light to reach the student’s eyes after the flash?
Light travels at 3.0 × 108 m/s in the air. How long, t1, in seconds did it take the light to reach the student’s eyes after the flash?
Queation 2.
Problem 2: Dave needs to get groceries from the store, which is a distance D = 2.8 km east of his house. Dave rides his bike to the store at a constant speed of v1 = 6.1 m/s, and rides back to his house at the slower speed of v2 = 2.5 m/s.
- Part (a) How long (in seconds) does it take for Dave to reach the store?
- Part (b) In seconds, how long does the whole trip take?
How long (in seconds) does it take for Dave to reach the store?
- Part (c) How long does the trip take in minutes?
- Part (d) How much distance, in kilometers, did Dave travel during the whole trip?
- Part (e): What is the magnitude of Dave’s displacement, in km, for the entire trip?
- Part (f): What is the direction of Dave’s displacement for the entire trip?
What is the direction of Dave’s displacement for the entire trip?
Question 3.
Problem 3: A particle’s position along the x-axis is described by the function
x(t) = A t + B t2,
where t is in seconds, x is in meters, and the constants A and B are given below.
Randomized Variables
A = -4.4 m/s B = 6.5 m/s2
- Part (a) Input an expression, in terms of the variables A, B, and t, for the velocity of the particle as a function of time.
- Part (b) At what time, in seconds, is the particle’s velocity zero?
Question 4.
Problem 4: A stone is dropped from rest from the top of a building. It takes Δt = 4.5 s for it to reach the ground.
- Part (a): What is the initial velocity, vi, of the stone in m/s?
- Part (b): What is the value of the magnitude of acceleration, in m/s2?
- Part (c): Express the final velocity vf of a object travelling with an acceleration a for a time period Δt which starts with an initial velocity vi.
- Part (d): Calculate the magnitude of vf in m/s.
- Part (e): Express the displacement Δy of an object travelling with acceleration a during a time period Δt that has an initial velocity vi.
- Part (f): Calculate the magnitude of Δy in meters.
Calculate the magnitude of Δy in meters.
Express the displacement Δy of an object travelling with acceleration a during a time period Δt that has an initial velocity vi.
Queation 5.
Problem 5: The position of a jet car is depicted in the line graph.
By analyzing the curve determine the jet car’s acceleration in meters per square second.
By analyzing the curve determine the jet car’s acceleration in meters per square second.
Queation 6.
Problem 6: A runner is at the starting gate and hears the starting gun. He begins running with a constant acceleration ai = 0.45 m/s2. He crosses the finish line at d = 100 m and then begins slowing down. It takes him tr to cross the finish line. It takes him ts = 8.5 s to return to rest after crossing the finish line. Use the given coordinate system where x is positive to the right.
- Part (a): Find an expression for the time it takes for the runner to cross the finish line, tr, from the start in terms of d and ai.
- Part (b): Using only acceleration, ai, and time, tr, write an expression for the runner’s final speed, vr, when he crosses the finish line.
- Part (c): Using the expressions you have derived, find a numeric value for the runner’s constant acceleration, ar (in meters per square second), after he crosses the finish line and is slowing again to rest.
Using the expressions you have derived, find a numeric value for the runner’s constant acceleration, ar (in meters per square second), after he crosses the finish line and is slowing again to rest.
Queation 8.
Problem 8: In a slap shot, a hockey player accelerates the puck from a velocity of 7.5 m/s to 39 m/s in one direction.
- If this shot takes 3.61 × 10-2 s, calculate the distance, in meters, over which the puck accelerates.
If this shot takes 3.61 × 10-2 s, calculate the distance, in meters, over which the puck accelerates.
Question 9.
Problem 9: A ball is thrown upward from the ground with initial velocity vi = 15 m/s and ultimately reaches height of h above the ground. Neglect air resistance.
- Part (a) What is the acceleration of the ball when it is in the air, in m/s2?
- Part (b) What is the velocity of the ball, vf, when it reaches the top of its trajectory, in m/s?
- Part (c) Write an expression for the maximum height, h, the ball reaches in terms of vf, vi, and a.
- Part (d) Calculate the numerical value of h, in meters.
- Part (e) Write an expression for the time it takes for the ball to travel from the ground to the top, Δt, in terms of vi, vf, and a.
- Part (f) Calculate the numerical value of Δt in seconds.
- Part (g) What is the total displacement, Δyt in meters, of the ball going through its entire motion; traveling from the ground to the top and then falling back to the ground?
- Part (h) Write an expression for the total time of flight for the ball; that is, the time from when it is launched to when it lands back on the ground. Express this time, Δtt, in terms of vi and a.
- Part (i) Calculate the numerical value of Δtt in seconds.
- Part (j) Express Δtt in terms of Δt calculated above, by comparing the result of Part (i) with the result of Part (f).
- Part (k) Express the velocity of the ball right before it hits the ground, vf, in terms of vi, Δtt and a.
- Part (l) Express vf in terms of vi.
Question 10.
Problem 10: Gravitational acceleration on the moon is one sixth of that on Earth. A ball released from rest above the surface falls from height d in a time of t = 1.5 seconds.
- Part (a) Write an expression for the final velocity vf of the ball when it impacts the surface of the moon assuming it is dropped from rest. This expression should be in terms of only, g (the gravitational acceleration on Earth), and time, t.
- Part (b) Calculate the final velocity, vf, numerically in m/s.
- Part (c) Calculate the height, d (in meters), from which the ball was dropped.
- Part (d) From how high up would this ball need to be dropped on the earth, de (in meters), if it took the same time to reach the ground as it did on the moon?
Question 11.
Problem 11: A dolphin in an aquatic show jumps straight up out of the water at a velocity of 14.5 m/s.
- Part (a) How high does his body rise above the water in meters?
- Part (b) How long is the dolphin in the air in seconds? Neglect any effects due to his size or orientation.
Question 12.
Problem 12: Suppose a man drops a rock into a dark well and, using precision equipment, you measure the time for the sound of a splash to return.
- Part (a) Neglecting the time required for sound to travel up the well, calculate the distance to the water if the sound returns in 1.9 s in meters.
- Part (b) Now calculate the height of the well taking into account the time for sound to travel up the well. The speed of sound is 331.5 m/s in this well.
Now calculate the height of the well taking into account the time for sound to travel up the well. The speed of sound is 331.5 m/s in this well.
Question 13.
Problem 13: The velocity vs. time graph of the motion of an object is shown in the figure.
Choose the correct acceleration vs. time graph.
Q 13 The velocity vs. time graph of the motion of an object is shown in the figure.
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