pg6

                         Grade 7Y Science Quiz # 2: Unit 3 � Structural Strength & Stability

Name: _________________________                                                                     Date: May 4, 2006

I) Multiple Choices: Choose the correct letter using the spaces (lines) provided. (20 Marks)

1) ______ This force can cause parts of a material to slide past one another in opposite directions.
a) tension             b) shear                    c) compression               d) torsion

2) ______ When a straight material becomes curved, one side squeezes together and the other side stretches apart. This action is called ?
a) compressing    b) belting                    c) buckling                      d) bending

3) ______ This force pushes material together. When a material is in this state, it tends to become shorter.
a) shear             b) compression            c) torsion                         d) tension

4) ______ This force stretches a material apart. When a material is in this state, it tends to become longer.
a) tension          b) torsion                     c) compression                 d) shear

5) ______ It is the rate at which velocity changes. It is a measured in meters per second squared
a) speed          b) momentum               c) acceleration                 d) velocity

6) ______ quantities have a magnitude but not a direction.
a) vector        b) scalar                      c) torque                          d) momentum

7) ______ quantities have both magnitude and a direction.
a) vector        b) scalar                     c) torque                          d) momentum

8) _______ It is the product of the mass of a body and its velocity:
a) force            b) weight                    c) torque                          d) momentum

9) ______ It is defined as a push or pull:
a) force         b) gravity                     c) acceleration                   d) velocity

10) _____ It is calculated by multiplying the magnitude of the applied force and the rotation pivot of the object
a) force         b) weight                    c) torque                          d) momentum

II) Short Answers: Answer the following questions: (18 marks)

1. This force produces compression in one surface and tension in the opposite surface in called bending

2. What force is applied when cutting with scissors?     shear

3. What force is applied when twisting a wet tower?     torsion

4. What force is applied when an elastic band is pulled in opposite directions?   tension

5. What force is applied when you squeeze a rubber ball?     compression

6. The magnitude of a force is measured in   Newton

7. Torque is calculated by multiplying F X r

8. The force is measured in Newton (N). 1 N = 1 kg. 1m/1S2

9. Examples of force are: electricity, magnatism, wind, and gravity.

10.Examples of scalar quantities are: mass, time, speed, etc.

11. Examples of vector quantities are: velocity, acceleration, force ...etc.

12. Describe the followings:
a) Tension:              a pulling force
b) Compression:      a pushing-together force
c) Torsion:              a twisting force
d) Shear:                 a force that uses two parallel but opposite forces

III) Problem Solving: Answer the following questions. Show all your work, formulas, and units: (12 Marks)
1. Adam travelled a total distance of 500 km North. His trip took 5 hours. Find the followings:

A) The velocity
v = d = 500 km = 100 km/h
      t     5 h

B) The acceleration
a = v = 100 km/h = 20 km/h2
   t        5 h

2. What is the weight of a 10 kg rock?
w = m X g = 10 kg X 10 m/s2 = 100 N

3. Find the force of an object with a mass of 5 kg and acceleration of 3 m/s2.
F = ma = 5 kg x 3 m/s2 = 15 N