A car is waiting at an intersection. When the traffic light turns green, the car
ID: 1417723 • Letter: A
Question
A car is waiting at an intersection. When the traffic light turns green, the car starts moving. After some time the car comes to rest at another traffic light. The figure below shows the velocity of the car as a function of time.
What is the acceleration of the car in the first stage?
What is the acceleration of the car in the third stage?
What is the total distance travelled by the car between the two traffic lights?
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A car is initially at rest on a straight road. The histgram shows the car's acceleration along that road as a function of time.
Calculate the speed of the car at t = 4 s.
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Two rocks are thrown simultaneously from the top of a very tall tower with identical speeds of v = 9.10 m/s, but in two different directions. (See figure.)
One of them is thrown with an angle of 10.0 degrees below the horizontal, the other one at an angle of 50.0 degrees above the horizontal. How far will the rocks be from each other after 4.10 s? (Neglect air resistance and assume that the rocks will not hit the ground.)
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Can someone please help me out with these problems? I'm having a lot of trouble and I really need to know how to do these problems.
Explanation / Answer
1) the acceleration of the car in the first stage = ( 9 - 0)/4 = 2.25 m/sec2
the acceleration of the car in the third stage = (0 - 8)/5 = - 1.6 m/sec2
total distance travelled by the car between the two traffic lights = (0.5 * 9 * 4) + 25.5 + (0.5 * 8 * 5)
= 63.5 m
2) the speed of the car at t = 4 s = 5 - 2 * 1
= 3 m/sec
3) Here, S1x = 9.10 * cos10 * 4.10
= 36.743 m
S2x = 9.10 * cos50 * 4.10
= 23.98 m
=> far will the rocks be from each other after 4.10 s = 36.743 - 23.98
= 12.763 m
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