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

Name: _________________________                                                                     Date: May 3rd , 2006

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

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

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

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

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

5) ______ 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

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

7) ______ 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

8) ______ 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

9) ______ 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

10) ______ 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

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. A stretching or pulling force within a structure, or part of a structure is called tension
3. A force within a structure that squeezes or pushes is called compression
4. A twisting force within a structure created by applying opposite rotational forces is called torsion
5. The forces that act in opposite directions along the same plane inside an object is called shear
6. The magnitude of a force is measured in       Newton
7. Torque is calculated by multiplying FX r
8. The force is measured in Newton (N). 1 N = 1 kg. 1m/s2
9. Examples of force are:   electricity, magnatism, friction, nuclear, wind, gravity, etc.
10. Examples of scalar quantities are: mass, volume, time, speed , etc.
11. Examples of vector quantitiesre:    velocity, force, acceleration, etc.

2.   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 a opposite forces

III) Problem Solving: Answer the following questions. Show all your work, formulas, and units: (12 Marks)

1. Daniel travelled a total distance of 400 km North. His trip took 4 hours. Find the followings:

A) The velocity

v = d = 400 km = 100 km/h
      t        4 h

B) The acceleration

a = v = 100 km/h = 25 km/h2
      t         4 h

2. What is the weight of a 20 kg rock?

w = m x g
   = 20 kg x 10 m/s2
   = 200 N

3. Find the force of an object with a mass of 6 kg and acceleration of 5 m/s2.
F = m x a
   = 6 kg x 5 m/s2
   = 30 N