Laws of Motion
Q. If a block is on a horizontal surface and a force is applied at an angle, how does this affect the normal force acting on the block?
A.
Increases normal force
B.
Decreases normal force
C.
No effect on normal force
D.
Depends on the angle
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Solution
Applying a force at an angle reduces the normal force because part of the applied force acts vertically upward, counteracting the weight of the block.
Correct Answer: B — Decreases normal force
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Q. If a body is moving in a circular path with a constant speed, which of the following statements is true?
A.
The body is in equilibrium
B.
The net force acting on the body is zero
C.
The body experiences a centripetal force
D.
The body has no acceleration
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Solution
A body moving in a circular path with constant speed experiences a centripetal force directed towards the center of the circle.
Correct Answer: C — The body experiences a centripetal force
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Q. If a body is moving in a circular path with a radius of 10 m and completes one full revolution in 5 seconds, what is its angular velocity?
A.
0.2 rad/s
B.
1.25 rad/s
C.
2 rad/s
D.
4 rad/s
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Solution
Angular velocity (ω) = 2π/T = 2π/5 = 1.25 rad/s.
Correct Answer: B — 1.25 rad/s
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Q. If a body is moving in a circular path with uniform speed, which of the following statements is true?
A.
The body has no acceleration
B.
The body has constant velocity
C.
The body experiences centripetal acceleration
D.
The body moves in a straight line
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Solution
The body experiences centripetal acceleration directed towards the center of the circle.
Correct Answer: C — The body experiences centripetal acceleration
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Q. If a body moves in a circular path with a constant speed, which of the following statements is true?
A.
The body has zero acceleration
B.
The body has constant acceleration
C.
The body has uniform velocity
D.
The body experiences centripetal acceleration
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Solution
The body experiences centripetal acceleration directed towards the center of the circle.
Correct Answer: D — The body experiences centripetal acceleration
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Q. If a car accelerates from rest to 20 m/s in 5 seconds, what is its acceleration?
A.
2 m/s²
B.
4 m/s²
C.
5 m/s²
D.
10 m/s²
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Solution
Acceleration a = (final velocity - initial velocity) / time = (20 m/s - 0) / 5 s = 4 m/s².
Correct Answer: B — 4 m/s²
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Q. If a car is moving on a flat road and suddenly turns, what type of friction is responsible for the car's ability to turn without skidding?
A.
Static friction
B.
Kinetic friction
C.
Rolling friction
D.
Fluid friction
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Solution
Static friction is responsible for providing the necessary centripetal force to keep the car moving in a circular path without skidding.
Correct Answer: A — Static friction
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Q. If a force of 12 N is applied to a 4 kg object, what is the resulting acceleration?
A.
2 m/s²
B.
3 m/s²
C.
4 m/s²
D.
5 m/s²
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Solution
Using F = ma, we find a = F/m = 12 N / 4 kg = 3 m/s².
Correct Answer: B — 3 m/s²
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Q. If a force of 15 N is applied to a mass of 3 kg, what is the net force acting on the mass if there is a frictional force of 5 N opposing the motion?
A.
10 N
B.
15 N
C.
20 N
D.
5 N
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Solution
Net force = applied force - frictional force = 15 N - 5 N = 10 N.
Correct Answer: A — 10 N
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Q. If a force of 15 N is applied to a mass of 3 kg, what is the net force acting on the mass if it is also experiencing a frictional force of 5 N?
A.
10 N
B.
15 N
C.
20 N
D.
5 N
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Solution
Net force = applied force - frictional force = 15 N - 5 N = 10 N.
Correct Answer: A — 10 N
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Q. If a force of 30 N is applied to a mass of 10 kg, what is the net force acting on the mass if there is a frictional force of 10 N opposing the motion?
A.
20 N
B.
30 N
C.
40 N
D.
10 N
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Solution
Net force = applied force - frictional force = 30 N - 10 N = 20 N.
Correct Answer: A — 20 N
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Q. If a stone is tied to a string and whirled in a horizontal circle of radius 2 m at a speed of 4 m/s, what is the tension in the string?
A.
2 N
B.
4 N
C.
8 N
D.
16 N
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Solution
Centripetal force (F_c) = mv²/r. Assuming mass (m) = 1 kg, F_c = 1(4²)/2 = 8 N.
Correct Answer: C — 8 N
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Q. If a stone is tied to a string and whirled in a horizontal circle of radius 2 m at a speed of 4 m/s, what is the tension in the string if the mass of the stone is 1 kg?
A.
2 N
B.
4 N
C.
8 N
D.
10 N
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Solution
Centripetal force = m(v²/r) = 1(4²/2) = 8 N. Tension in the string = 8 N.
Correct Answer: C — 8 N
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Q. If the angle of inclination of a plane increases, what happens to the static frictional force acting on an object resting on the plane?
A.
Increases
B.
Decreases
C.
Remains constant
D.
Becomes zero
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Solution
As the angle increases, the component of gravitational force parallel to the plane increases, which can lead to a decrease in static friction until it reaches its maximum value.
Correct Answer: B — Decreases
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Q. If the angle of inclination of a plane increases, what happens to the static friction force acting on an object resting on the plane?
A.
Increases
B.
Decreases
C.
Remains constant
D.
Becomes zero
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Solution
As the angle increases, the component of gravitational force parallel to the plane increases, which can lead to a decrease in static friction until it reaches its maximum value.
Correct Answer: B — Decreases
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Q. If the angular velocity of a rotating object is doubled, what happens to its centripetal acceleration?
A.
It remains the same
B.
It doubles
C.
It quadruples
D.
It halves
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Solution
Centripetal acceleration (a_c) = ω²r. If ω is doubled, a_c becomes (2ω)²r = 4ω²r.
Correct Answer: C — It quadruples
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Q. If the period of a satellite in a circular orbit is T, what is the relationship between T and the radius r of the orbit?
A.
T ∝ r
B.
T ∝ r²
C.
T ∝ √r
D.
T ∝ 1/√r
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Solution
T = 2π√(r³/GM), thus T ∝ √r.
Correct Answer: C — T ∝ √r
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Q. If the speed of an object in circular motion is doubled, what happens to the centripetal acceleration?
A.
It remains the same
B.
It doubles
C.
It quadruples
D.
It halves
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Solution
Centripetal acceleration a_c = v²/r. If v is doubled, a_c increases by a factor of 4.
Correct Answer: C — It quadruples
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Q. If two forces of 10 N and 15 N act in the same direction on an object, what is the resultant force?
A.
5 N
B.
10 N
C.
15 N
D.
25 N
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Solution
The resultant force is the sum of the two forces: 10 N + 15 N = 25 N.
Correct Answer: D — 25 N
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Q. If two forces of 10 N and 15 N act on an object in the same direction, what is the net force acting on the object?
A.
5 N
B.
10 N
C.
15 N
D.
25 N
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Solution
Net force = 10 N + 15 N = 25 N.
Correct Answer: D — 25 N
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Q. If two forces of 10 N and 5 N act in the same direction on an object, what is the net force?
A.
15 N
B.
5 N
C.
10 N
D.
20 N
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Solution
The net force is the sum of the forces: 10 N + 5 N = 15 N.
Correct Answer: A — 15 N
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Q. If two forces of 5 N and 10 N act in the same direction on an object, what is the net force?
A.
15 N
B.
5 N
C.
10 N
D.
0 N
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Solution
Net force = 5 N + 10 N = 15 N.
Correct Answer: A — 15 N
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Q. If two objects of masses 3 kg and 5 kg collide elastically, what is the final velocity of the 3 kg object if it was initially at rest and the 5 kg object was moving at 10 m/s?
A.
0 m/s
B.
3 m/s
C.
5 m/s
D.
10 m/s
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Solution
Using conservation of momentum and kinetic energy, the final velocity of the 3 kg object can be calculated to be 3 m/s.
Correct Answer: B — 3 m/s
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Q. In a conical pendulum, if the angle of the string with the vertical is increased, what happens to the horizontal component of the tension?
A.
Increases
B.
Decreases
C.
Remains the same
D.
Becomes zero
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Solution
As the angle increases, the horizontal component of tension increases to provide the necessary centripetal force.
Correct Answer: A — Increases
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Q. In a uniform circular motion, which of the following quantities remains constant?
A.
Velocity
B.
Acceleration
C.
Speed
D.
Centripetal force
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Solution
In uniform circular motion, speed remains constant while velocity and acceleration change direction.
Correct Answer: C — Speed
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Q. In uniform circular motion, which of the following quantities remains constant?
A.
Speed
B.
Velocity
C.
Acceleration
D.
Centripetal force
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Solution
In uniform circular motion, the speed remains constant, but velocity and acceleration change direction.
Correct Answer: A — Speed
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Q. In uniform circular motion, which of the following statements is true?
A.
Velocity is constant
B.
Acceleration is zero
C.
Speed is constant
D.
Net force is zero
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Solution
In uniform circular motion, speed is constant but velocity changes due to direction change.
Correct Answer: C — Speed is constant
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Q. In which scenario would the frictional force be at its maximum?
A.
When an object is at rest
B.
When an object is sliding
C.
When an object is rolling
D.
When an object is in free fall
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Solution
The maximum frictional force occurs when an object is at rest, just before it starts to slide, which is characterized by static friction.
Correct Answer: A — When an object is at rest
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Q. In which scenario would the frictional force be zero?
A.
A block sliding down a frictionless ramp.
B.
A block at rest on a flat surface.
C.
A block moving on a rough surface.
D.
A block in free fall.
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Solution
Frictional force is zero when there is no contact force opposing the motion, such as a block sliding down a frictionless ramp.
Correct Answer: A — A block sliding down a frictionless ramp.
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Q. Two blocks of masses 2 kg and 3 kg are connected by a light string over a frictionless pulley. If the 3 kg block is released from rest, what is the acceleration of the system?
A.
1.2 m/s²
B.
2 m/s²
C.
3 m/s²
D.
4 m/s²
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Solution
Using Newton's second law, the net force is (3 kg - 2 kg) * g = 1 kg * 9.8 m/s². The total mass is 5 kg, so a = F/m = 9.8 N / 5 kg = 1.96 m/s², approximately 2 m/s².
Correct Answer: B — 2 m/s²
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