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KEAM Optics — practice questions — page 2

Explore 89 free Optics questions in KEAM Physics. Open each question or exercise to read its content, reference answers and available explanation.

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Optics questions and exercises with answers

Showing questions 31–60 of 89.

Newton's first law of motion is also known as the law ofRead the answer and worked solution →A cricket ball of mass 150 g moving at (3i+4j) m/s is hit to -(3i+4j) m/s. The magnitude of momentum change isRead the answer and worked solution →Conservation of linear momentum in a collision follows directly fromRead the answer and worked solution →A force F acts on a 2 kg body for 3 s, changing its speed from 2 m/s to 8 m/s along the line of F. The magnitude of F isRead the answer and worked solution →The maximum static friction force on a body is f = μN. Static friction is best described asRead the answer and worked solution →A 10 kg block on a frictionless surface is pulled by 20 N horizontally and 20 N at 60° above horizontal. The horizontal acceleration isRead the answer and worked solution →Impulse equalsRead the answer and worked solution →A body in equilibrium under several forces hasRead the answer and worked solution →A 0.5 kg ball hits a wall at 10 m/s and rebounds at 10 m/s. The impulse on the ball isRead the answer and worked solution →Newton's second law in vector form isRead the answer and worked solution →A lift accelerates upward at 2 m/s². The apparent weight of a 50 kg person (g=10) isRead the answer and worked solution →Two blocks of 2 kg and 3 kg connected by a string are pulled by 10 N on the 3 kg block (frictionless). The acceleration isRead the answer and worked solution →The SI unit of force, the newton, equalsRead the answer and worked solution →A passenger standing in a bus is thrown backward when the bus suddenly starts moving forward. This is best explained by:Read the answer and worked solution →One newton is defined as the force that gives a mass of 1 kg an acceleration of:Read the answer and worked solution →The linear momentum of a body is defined as the product of its:Read the answer and worked solution →The impulse of a force has the same dimensions as:Read the answer and worked solution →The action and reaction forces of Newton's third law:Read the answer and worked solution →For a given pair of surfaces, the coefficient of kinetic friction is usually:Read the answer and worked solution →A constant force of 20 N acts on a 5 kg body initially at rest. Its speed after 3 s is:Read the answer and worked solution →A 0.15 kg ball moving at 12 m s⁻¹ is hit straight back along its path with the same speed. The magnitude of the impulse on the ball is:Read the answer and worked solution →A 0.04 kg bullet moving at 90 m s⁻¹ is stopped after penetrating 0.6 m into a block. The average resistive force is:Read the answer and worked solution →A block just begins to slide down an incline when the angle of inclination is 30°. The coefficient of static friction between block and incline is:Read the answer and worked solution →A 0.02 kg bullet is fired with a speed of 300 m s⁻¹ from a 4 kg gun. The recoil speed of the gun is:Read the answer and worked solution →A 50 kg person stands on a weighing scale inside a lift accelerating upward at 2 m s⁻² (g = 10 m s⁻²). The scale reads:Read the answer and worked solution →A 0.5 kg stone tied to a string is whirled in a horizontal circle of radius 2 m at a speed of 4 m s⁻¹. The tension in the string is:Read the answer and worked solution →The maximum speed at which a car can round an unbanked circular turn of radius 150 m without skidding is (μs = 0.6, g = 10 m s⁻²):Read the answer and worked solution →For a 3 kg block connected over a frictionless pulley to a 20 kg trolley (μk = 0.04, g = 10 m s⁻²), the tension in the connecting string is:Read the answer and worked solution →A net force F = 6t newton (t in seconds) acts on a 2 kg body initially at rest. The speed of the body at t = 4 s is:Read the answer and worked solution →A block slides down a rough incline of 30° with coefficient of kinetic friction 0.2 (g = 10 m s⁻²). Its acceleration down the incline is:Read the answer and worked solution →

Worked practice questions

Newton's first law of motion is also known as the law of

  1. acceleration
  2. action-reaction
  3. inertia
  4. gravitation
Show answer and solution

Correct answer: C. inertia

The first law (a body stays at rest or in uniform motion unless acted on by a net force) defines inertia.

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A cricket ball of mass 150 g moving at (3i+4j) m/s is hit to -(3i+4j) m/s. The magnitude of momentum change is

  1. 0
  2. 3.0 kg·m/s
  3. 1.5 kg·m/s
  4. 0.75 kg·m/s
Show answer and solution

Correct answer: C. 1.5 kg·m/s

We have Δp = m(v−u). That is Δp = 0.15·(−2)(3i+4j). So Δp = −0.3(3i+4j). |Δp| = 0.3·√(9+16) = 0.3·5 = 1.5 kg·m/s.

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Conservation of linear momentum in a collision follows directly from

  1. Newton's third law
  2. conservation of energy
  3. the law of gravitation
  4. Newton's first law only
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Correct answer: A. Newton's third law

Equal-and-opposite internal forces (third law) make the total momentum change zero, so momentum is conserved.

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