Question 1
Suppose you drop a rock into a dark well and, using precision equipment, you measure the time for the sound of a splash to return.
(a) Neglecting the time required for the sound to travel up the well, calculate the distance to the water if the sound returns in 2.2000 s.
(b) Now calculate the distance taking in to account the time taken for the sound to travel up the well. The speed of sound is 320mis in this well.
Question 2
In a test a new electric car, of mass 750 kg. (including the driver) accelerates uniformly from rest to 100 km/h while covering 115 m. The coefficient of rolling resistance between the car and the road is 0.027.
(a) What is the acceleration?
(b) What horizontal force, including that to overcome friction (rolling resistance), is the car exerting on the road?
Question 3
A steel plate of uniform thickness 4mm has the shape shown. Locate the position of the centroid of the plate relative to point "O"
Question 4
For the lever below.
(a) Determine the centre of gravity relative to the pivot point A in the horizontal direction only (Excluding the guide rod)
(b) Draw a free body diagram for the lever showing all the forces acting on it. If the lever is manufactured from steel of density 7000kg/m3 determine the force in the spring required to hold the lever horizontal when the guide rod (weight 20 N) rests on the semi-circular end piece of the lever.
Question 5
(a) A contestant in a winter sporting event pushes a 54.0-kg block of ice across a frozen lake as shown.
Calculate the minimum force F he must exert to get the block moving.
Research a suitable coefficient of friction and give reasons for your selection
(b) Repeat but this time with the contestant pulling the block of ice with a rope over his shoulder at the same angle above the horizontal as shown.
Calculate the minimum force F he must exert to get the block moving.
(c) Which method of sliding a block of ice requires less force-(a) pushing or
(b) pulling at the same angle above the horizontal? And explain why this is so.
Question 6
(a) Find the second moment of area and radius of gyration about the axis XX for the beam section shown
(b) Determine the position of the centroid of the section.
(c) Calculate the second moment of area about an axis through the centroid parallel to axis XX.
