GO (a) If a particle’s position is given by x = 4 − 12 t + 3 t 2 (where t is in seconds and x is in meters), what is its velocity at t = 1 s? (b) Is it moving in the positive or negative direction of x just then? (c) What is its speed just then? (d) Is the speed increasing or decreasing just then? (Try answering the next two questions without further calculation.) (e) Is there ever an instant when the velocity is zero? If so, give the time t ; if not, answer no. (f) Is there a time after t = 3 s when the particle is moving in the negative direction of x ? If so, give the time t ; if not, answer no.
GO (a) If a particle’s position is given by x = 4 − 12 t + 3 t 2 (where t is in seconds and x is in meters), what is its velocity at t = 1 s? (b) Is it moving in the positive or negative direction of x just then? (c) What is its speed just then? (d) Is the speed increasing or decreasing just then? (Try answering the next two questions without further calculation.) (e) Is there ever an instant when the velocity is zero? If so, give the time t ; if not, answer no. (f) Is there a time after t = 3 s when the particle is moving in the negative direction of x ? If so, give the time t ; if not, answer no.
GO (a) If a particle’s position is given by x = 4 − 12t + 3t2(where t is in seconds and x is in meters), what is its velocity at t = 1 s? (b) Is it moving in the positive or negative direction of x just then? (c) What is its speed just then? (d) Is the speed increasing or decreasing just then? (Try answering the next two questions without further calculation.) (e) Is there ever an instant when the velocity is zero? If so, give the time t; if not, answer no. (f) Is there a time after t = 3 s when the particle is moving in the negative direction of x? If so, give the time t; if not, answer no.
Steel train rails are laid in 13.0-m-long segments
placed end to end. The rails are laid on a winter
day when their temperature is -6.0° C.
Part A
How much space must be left between adjacent rails if they are just to touch on a summer day when their
temperature is 32.0°C?
Express your answer with the appropriate units.
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Part B
If the rails are originally laid in contact, what is the stress in them on a summer day when their temperature is
32.0°C?
Express your answer in pascals. Enter positive value if the stress is tensile and negative value if the
stress is compressive.
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help me with this and the step I am so confused. It should look something like the figure i shown
Part A
In an effort to stay awake for an all-night study
session, a student makes a cup of coffee by first
placing a 200 W electric immersion heater in
0.250 kg of water.
How much heat must be added to the water to raise its temperature from 20.5° C to 95.0°C?
Express your answer in joules.
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Part B
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How much time is required? Assume that all of the heater's power goes into heating the water.
Express your answer in seconds.
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