PH2100 EXAM I Form APage 1SPRING 2001
Problems and Short Answer Questions
Write your answer to each of the following on the line provided on the answer sheet.
1.Following the rules of significant figures, calculate: (Report your answers in scientific notation)
(a)8.65 + 7.346 + 1.00034
(b)18757.3 - 18742.1
2.The displacement of an object as a function of time is given by
x = 2.20 t + 1.05 t3
where x is in meters and t is in seconds.
(a)Find the instantaneous velocity at 2.00 seconds.
(b)Find the instantaneous acceleration at 2.00 seconds.
(c)Find the average velocity over the time interval between 0.00 and 4.00 seconds.
3.A jetliner touches down at a speed of 75.0m/s (equals 270km/h). On landing, the plane decelerates at 4.50m/s2. What is the minimum runway length on which the jetliner can land?
4.How fast would a car have to drive around a curve 50.0m in radius in order for its acceleration to be 9.80m/s2?
5.Given two vectors A=5.05i+3.88j and B=5.05i-11.0j+2.00k calculate
(a)A + B
(b)B = magnitude of B
(c)direction of A measured from the +x-axis (report angle in degrees)
6.A motorboat can run at 6.78m/s in still water. Suppose the water in a river flows at 1.24m/s with respect to the bank and the river is 0.565km wide.
(a)If the boat heads directly upstream, how much time will it take to travel from the boat dock to a bridge 1.15km away?
(b)If the boat heads straight across the river, what will its speed be relative to the bank?
7.A chunk of lava is ejected from a volcano. It takes a total time of 5.50s to fall back to its original height.
(a)How high did it get thrown?
(b)How fast was it moving upward when ejected?
8.A projectile is launched from the top of a roof 5.50m high at an angle of elevation of 42.1o with a speed of 85.3m/s. Ignore air resistance.
(a)Calculate the horizontal component of its velocity.
(b)How much time will it take for the projectile to reach the highest point in its trajectory?
(c)How far away from the launch point will the projectile strike the ground?
Multiple Choice
Circle the letter corresponding to the correct choice on the answer sheet.
9.Which of the following choices is not possible for a particle moving in one dimension?
(a)The velocity is positive and the acceleration is negative.
(b)The velocity is negative and the acceleration is negative.
(c)In a time t, the average velocity is negative and the total displacement is negative.
(d)In a time t, the average velocity is positive and the total displacement is negative.
(e)None of the above
10.Suppose that two quantities A and B have different dimensions. Which of the following arithmetic operations could be physically meaningful?
(a)2A + 3B
(b)B - A
(c)A / B
(d)all of the above
(e)none of the above
11.On the moon, a rock is dropped from rest at the same instant that a ball at the same elevation is thrown horizontally. Which of the following is true?
(a)The rock and the ball will reach the surface of the moon at the same time.
(b)The ball will reach the surface of the moon before the rock.
(c)The ball will reach the surface of the moon after the rock.
(d)The ball will reach the surface of the moon with a larger speed.
(e)The ball and the rock will reach the surface of the moon with the same speed.