# Extra Physics flashcards January 2023

1
Q
1. A number of forces acting on an object may be replaced by a single force that has the same effect as all the original forces acting together. This single force is called the ……………… force.
A

resultant

2
Q
1. What is the resultant force when the forces on an object are balanced?
A

Zero or 0 N

3
Q
1. State the effect of unbalanced forces on a moving object if the resultant force direction is in the direction that the object is moving. Which one of the following is true? 1) It will stay stationary 2) It will keep moving at a constant speed 3) It will speed up 4) It will slow down
A

3) It will speed up

4
Q
1. State the effect of balanced forces (zero resultant) on a moving object. Which one of the following is true? 1) It will stay stationary 2) It will keep moving at a constant speed 3) It will speed up 4) It will slow down
A

2) It will keep moving at a constant speed

5
Q
1. State the effect of balanced forces (zero resultant) on a stationary (not moving) object. Which one of the following is true? 1) It will stay stationary 2) It will keep moving at a constant speed 3) It will speed up 4) It will slow down
A

1) It will stay stationary

6
Q
1. State the effect of unbalanced forces on a stationary (not moving) object. Which of the following is true? 1) It will stay stationary 2) It will keep moving at a constant speed 3) It will speed up 4) It will slow down
A

3) It will speed up

7
Q
1. State the effect (if any) of unbalanced forces on a moving object if the resultant force is in the opposite direction to the direction of the moving object. Which one of the following is true? 1) It will stay stationary 2) It will keep moving at a constant speed 3) It will speed up 4) It will slow down
A

4) It will slow down

8
Q
1. Why do surfaces that feel smooth still have friction?
A

Even smooth surfaces have microscopic hills and valleys (which resist movement)

9
Q
1. What force causes surfaces to wear away over time?
A

friction

10
Q
1. In addition to wearing away surfaces what other effect does friction cause when rubbing two objects together?
A

A rise in temperature

11
Q
1. Describe 2 uses of friction between solids
A

Without friction our feet would not be able to grip the road and we would be unable to walk / Friction is important in helping objects to slow down safely using brakes / [Also to strike a match]

12
Q
1. Describe a benefit of air resistance
A

Air resistance is the force that parachutes make use of to slow down someone who is falling from an aeroplane

13
Q
1. Why doesn’t a rocket in space need to use its engine to keep moving?
A

There is no friction or air resistance in space to slow it down. [Gravity is not zero in space]

14
Q
1. State the equation for speed
A

Speed = Distance/Time

15
Q
1. When distance is measured in metres and time is measured in seconds, what is speed measured in?
A

m/s

16
Q
1. Calculate the speed of an object moving a distance 10 m in 2 s.
A

Speed = Distance/ Time= 10 /2 = 5 m/s

17
Q
1. What word is used to describe an object that is speeding up?
A

Acceleration or accelerating

18
Q
1. For a spring what do we call the stretched length minus the unstretched length?
A

Extension

19
Q
1. What is the name of the law that springs obey? The law says that a spring’s extension doubles when the force doubles or extension is directly proportional to the stretching force.
A

Hooke’s Law

20
Q
1. Describe a risk assessment for the spring experiment
A

Hazard: Spring could break or come loose / Risk: damage eye / Precaution: Wear safety goggles