Physics for IGCSE & O level - Forces And Motion (Section 8)

1
What does the term 'dynamic friction' refer to?
Απάντηση
(C)
Friction that occurs when an object is in motion.
2
What direction do the forces act, according to Newton's third law?
Απάντηση
(B)
In opposite directions on different objects
3
Which of the following relates to work done on an object?
Απάντηση
(B)
When the object moves in the same direction as the force.
4
What happens to an object's acceleration if the net force acting on it doubles?
Απάντηση
(B)
The acceleration doubles.
5
If an object has constant speed, what is the acceleration?
Απάντηση
(A)
Zero
6
What happens to the air resistance as the speed of a skydiver increases?
Απάντηση
(C)
Air resistance increases.
7
What is the relationship between force, mass, and acceleration?
Απάντηση
(B)
Force = Mass * Acceleration
8
If a car is traveling at 15 m/s for 10 seconds, what distance does it cover?
Απάντηση
(B)
150 m
9
What does the slope represent in a distance-time graph?
Απάντηση
(A)
Speed
10
What does the text say about using the gradient in a distance-time graph?
Απάντηση
(C)
It tells you how much extra distance is covered in a period of time
11
When air resistance equals the force of gravity on a falling object, what is the resulting velocity?
Απάντηση
(C)
Constant
12
What is the relationship between force and acceleration?
Απάντηση
(C)
Force causes acceleration.
13
Which factor(s) influence the magnitude of centripetal force?
Απάντηση
A
B
C
14
Which of the following is the formula for Newton's Second Law of Motion?
Απάντηση
(B)
F = ma
15
Which term is best described as the opposition to the motion of the object?
Απάντηση
(D)
Friction
16
What happens to the momentum of a system when there are no external forces acting upon it?
Απάντηση
(D)
It remains constant.
17
In a speed time graph, what does a straight line parallel to the time axis indicate?
Απάντηση
(C)
Object is moving at a constant speed.
18
If the net force on an object is zero, what will be its state of motion?
Απάντηση
(C)
It will move at a constant velocity or remain at rest.
19
What is the effect of doubling the velocity of an object on its kinetic energy?
Απάντηση
(B)
It quadruples.
20
What does a curved line in a speed-time graph indicate?
Απάντηση
(C)
Non-uniform acceleration.
21
What is Newton's third law of motion?
Απάντηση
(A)
For every action, there is an equal and opposite reaction.
22
What happens to the weight of an object if you move it to a location with a lower gravitational field strength?
Απάντηση
(C)
The weight decreases.
23
What is an example of a situation where friction is desirable?
Απάντηση
(C)
Walking on a sidewalk.
24
What is the relationship between force and acceleration?
Απάντηση
(B)
Force causes acceleration.
25
What happens to the acceleration of an object if you double the net force acting on it, assuming the mass remains constant?
Απάντηση
(C)
The acceleration doubles.
26
Which of the following is the SI unit for acceleration?
Απάντηση
(A)
m/s²
27
Which quantities are considered as scalars?
Απάντηση
(A)
Distance and time
28
What does a decreasing velocity mean?
Απάντηση
(B)
The object's speed is decreasing.
29
What is the formula for calculating weight?
Απάντηση
(B)
Weight = mass * acceleration
30
Which of the following statements is true about weight?
Απάντηση
(B)
Weight is the force of gravity acting on an object.
31
What is the reaction force if an athlete pushes off the ground to jump?
Απάντηση
(B)
The ground pushing the athlete upwards.
32
What is the relationship between mass and inertia?
Απάντηση
(D)
Mass is a measure of inertia.
33
On a speed-time graph, a line with a negative slope indicates what?
Απάντηση
(C)
Negative acceleration (deceleration).
34
If a car's average speed is 30 m/s, how far does it travel in 2 minutes (120 seconds)?
Απάντηση
(C)
3600 m
35
What is the formula for acceleration?
Απάντηση
(B)
a = (v_f - v_i) / t
36
What is the acceleration of a free-falling object near the Earth's surface?
Απάντηση
(A)
9.8 m/s²
37
What is the action force when a person pushes a box across the floor?
Απάντηση
(C)
The force of the person on the box.
38
Which of the following is a unit of impulse?
Απάντηση
(B)
kg m/s
39
If the radius of a circle is doubled, while keeping the speed and mass constant, how does the centripetal force change?
Απάντηση
(B)
It halves.
40
What do we call the movement along a straight line?
Απάντηση
(C)
Linear motion.
41
Which of these statements are true about force?
Απάντηση
A
B
C
42
If you push a box with a force of 10 N, and friction exerts a force of 3 N, what is the net force on the box?
Απάντηση
(B)
7 N
43
If the forces on an object are unbalanced, the object will:
Απάντηση
(B)
Accelerate.
44
In the experiment to measure 'g' on the moon, what factors are involved?
Απάντηση
A
B
45
What is dynamic friction?
Απάντηση
(B)
Friction between surfaces in motion.
46
What can you determine from a speed-time graph?
Απάντηση
A
B
C
47
Which are correct statements about the distance-time graph?
Απάντηση
B
C
48
Which of the following are examples of forces?
Απάντηση
A
C
49
What is the relationship between the centripetal force and the mass of an object moving in a circle?
Απάντηση
(D)
The centripetal force increases as the mass increases.
50
What happens to an object's kinetic energy when it accelerates?
Απάντηση
(B)
It increases.