# SEC 3 Physics Quiz For SST Students - Dynamics

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Questions: 12 | Attempts: 309  Settings  Sec 3 Physics Quiz on Dynamics

• 1.

### The direction of the resultant force produced by the forces OX and OY acting on the point O as shown in the figure below is represented by

• A.

OP

• B.

OQ

• C.

OR

• D.

OS

A. OP
Explanation
The direction of the resultant force produced by the forces OX and OY acting on the point O can be represented by OP. This is because the forces OX and OY are acting in different directions, and the resultant force is the vector sum of these forces. The vector OP represents the direction and magnitude of the resultant force, with the tail of the vector at point O and the head pointing towards the direction of the force. Therefore, OP is the correct representation of the direction of the resultant force.

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• 2.

### A sledge of mass 25 kg is pulled across level ground with a horizontal force of 60 N. The constant force of friction is 20 N. What is the acceleration of the sledge? A 0.63 m/s2 B 1.6 m/s2 C 2.4 m/s2 D 3.2 m/s2

• A.

A

• B.

B

• C.

C

• D.

D

B. B
Explanation
The acceleration of an object can be calculated using Newton's second law of motion, which states that the acceleration is equal to the net force acting on the object divided by its mass. In this case, the net force is the horizontal force of 60 N minus the force of friction of 20 N, which results in a net force of 40 N. Dividing this by the mass of the sledge (25 kg) gives an acceleration of 1.6 m/s2.

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• 3.

### A constant horizontal force is applied to a body initially at rest on a smooth horizontal table. Which of the following quantities will not change during the application of the force?

• A.

The displacement of the body.

• B.

The velocity of the body.

• C.

The acceleration of the body.

• D.

The kinetic energy of the body.

C. The acceleration of the body.
Explanation
The acceleration of the body will not change during the application of the force. This is because acceleration is determined by the net force acting on an object and its mass, according to Newton's second law of motion (F = ma). In this scenario, a constant horizontal force is being applied, so the net force remains constant. As a result, the acceleration of the body will also remain constant.

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• 4.

### The following diagrams show two forces acting on a Block. In which case does the block have the smallest acceleration?

• A.

A

• B.

B

• C.

C

• D.

D

A. A
Explanation
In diagram A, the two forces acting on the block are equal in magnitude but opposite in direction, resulting in a net force of zero. According to Newton's second law of motion, F = ma, where F is the net force and a is the acceleration. Since the net force is zero, the acceleration of the block will also be zero. Therefore, diagram A represents the case where the block has the smallest acceleration.

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• 5.

### An object of mass m, is resting on a frictionless surface. When a force F is acting on the object, it produces an acceleration of 1 m/s2. If the force is increased to 2F and mass reduced by half, what will be the acceleration?

• A.

1/4 m/s2

• B.

1/2 m/s2

• C.

1 m/s2

• D.

4 m/s2

D. 4 m/s2
Explanation
When the force acting on the object is increased to 2F and the mass is reduced by half, the acceleration will increase. This is because the relationship between force, mass, and acceleration is given by Newton's second law of motion, which states that force is equal to mass multiplied by acceleration (F = ma). In this case, since the force is doubled and the mass is halved, the acceleration will be four times the original acceleration. Therefore, the acceleration will be 4 m/s2.

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• 6.

### Name the following types of forces which are either a push or a pull on an object. a. The gravitational pull on an object

weight, Weight, gravitational force, Gravitational force, Gravitational Force
Explanation
The correct answer includes the terms "weight," "gravitational force," and "Gravitational Force." These terms refer to the force exerted on an object due to gravity. Gravity is a force that pulls objects towards each other, and the weight of an object is the force with which it is pulled towards the center of the Earth. Therefore, these terms accurately describe the push or pull force exerted on an object due to gravity.

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• 7.

### Name the following types of forces which are either a push or a pull on an object. b. The pull by a stretched spring or rope       ____________

tension, Tension
Explanation
The correct answer is tension. When a spring or rope is stretched, it exerts a pulling force on the object it is attached to. This force is called tension. Tension can also be represented by the symbol "T".

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• 8.

### Name the following types of forces which are either a push or a pull on an object. c. The pull which opposes the movement of an object          ________________

Friction, friction, Frictional force, air resistance, Air Resistances, resistance
Explanation
The correct answer is friction. Friction is a force that opposes the movement of an object when it is in contact with another surface. It can either be a push or a pull depending on the direction of the movement.

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• 9.

### Name the following types of forces which are either a push or a pull on an object. 4. The push or pull between magnets                         ______________

magnetic force, Magnetic forces, magnetic forces
Explanation
The correct answer is "magnetic force". When two magnets are brought close to each other, they either attract or repel each other. This push or pull between magnets is known as the magnetic force. It is responsible for the interaction between magnets and is a fundamental force in nature. The magnetic force can be both attractive and repulsive, depending on the orientation of the magnets.

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• 10.

### Name the following types of forces which are either a push or a pull on an object. 5. The push or pull between electric charges ______________

Electric force, electric forces
Explanation
The push or pull between electric charges is known as electric force. Electric force is a fundamental force of nature that occurs between charged particles, such as electrons and protons. This force can either attract or repel charged objects, depending on their charges. Electric forces play a crucial role in various phenomena, including the behavior of electrons in atoms, the functioning of electronic devices, and the interaction between charged particles in electric fields.

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• 11.

### A hot air balloon has a total mass of 150 kg. What is the resultant force acting on the balloon if a) The balloon rises with an acceleration of 0.50 ms-2? (Enter the final answer with units in the given blank.)

300 N, 300N
Explanation
The resultant force acting on the balloon is equal to the product of its mass and acceleration according to Newton's second law of motion (F = m * a). In this case, the mass of the balloon is 150 kg and the acceleration is 0.50 m/s^2. Therefore, the resultant force is 150 kg * 0.50 m/s^2 = 75 N. Since the force is acting upwards, the answer is 75 N, 75 N.

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• 12.

### A hot air balloon has a total mass of 150 kg. What is the resultant force acting on the balloon if b) The balloon rises with a constant speed of 2.0 ms-1? (Enter the final answer with units in the given blank.) Back to top