Dynamics 1 Flashcards
Q. State the difference between scalar quantities and vector quantities.
A. Scalar quantities only have size (like 10m) but vector quantities have size and direction (like 10m south).
Q. Give 6 examples of scalar quantities.
A. Distance
Time
Energy
Mass
Power
Speed
(d.t.e.m.p.s)
Q. Give 6 examples of vector quantities.
A. Displacement
Air Resistance
Force
Weight
Acceleration
Velocity
(d.a.f.w.a.v)
Q. Explain how you would work out the average speed of a car travelling a certain distance.
A. Measure the time with a stop clock and measure the distance travelled using a trundle wheel. Then use
d = vt. (Long time)
Q. Explain how you would work out the instantaneous speed of a car travelling a certain distance
A. Measure the length of the car and use a light gate to calculate the time it takes to pass a point in its journey. Then use
d = vt. (Short time)
Q. Explain what is meant by the term acceleration.
A. The change in velocity per second.
Q. Explain how you could calculate the acceleration of a car.
A. Measure its initial velocity, its final velocity and the time taken to change velocity. Then use a = v-u
t
Q. State Newton’s 1st law of motion.
A. When the forces acting on an object are balanced its speed is constant
State Newton’s 2nd law of motion.
A. When the forces acting on an object are unbalanced then its speed is changing (accelerating).
Q. State Newton’s 3rd law of motion
A. For every action there is an equal and opposite reaction.
Q. Explain, in terms of forces, why a falling object reaches terminal velocity.
A. The weight and air resistance become balanced so it reaches a constant velocity (known as terminal velocity).
