SCIENCE: Check Your Learning Answers to 11.1 & 11.2

Question 1 You can find the center of gravity of a golf club by balancing it horizontally on your hand. You could hang the painting by one corner and mark a vertical line on the back, and then repeat for another corner. The intersection of the points is the approximate centre of gravity.

c) You could use a plumb line to locate the centre of gravity of a coat hanger. d) You could locate the center of gravity of a tennis racquet by balancing it horizontally on your hand.

Question Two The geometric center The center of the hole

Question Three A low center of gravity and a wide support base directly under the center of gravity provide good stability.

Question Four The center of gravity must be low, and the support base must be wide. The support base must be wide. The center of gravity must be directly over the support base.

Question Five A turtle is more stable because its center of gravity is much lower than a giraffe’s. My school building is more stable than the CN Tower because its center of mass is much lower and it has a wider support base. The CN Tower would not have to tilt very much in order for its CG to fall outside its support base.

11.2 Question One One way to strengthen a beam is to use a stronger material. Another way is to change the form of the beam. For example, an I-beam is a strong design. A third way to strengthen a beam is to use corrugation. A fourth way is to add a structural support, such as a tie, a strut, or a gusset.

Question Two A supported beam is supported at both ends. A cantilever is supported only at one end.

Question Three A canopy over a hotel entrance and a balcony on an apartment building are examples of cantilevers in my neighbourhood.