Where is the absolute gravitational potential energy of a body taken to be zero?
Correct answer B. At infinity
Subject / 480 questions
MDCAT ECAT Physics MCQs
Page 21 of MDCAT ECAT Physics multiple-choice questions with answers. Tap an option to check yourself.
Page 21 of 24
- Electromagnetic Induction 30
- Fluid Dynamics 30
- Electrostatics 30
- Electronics 30
- Electromagnetism 30
- Current Electricity 30
- Work and Energy 30
- Waves 30
- Vectors and Equilibrium 30
- Nuclear Physics 30
- Dawn of Modern Physics 30
- Thermodynamics 30
- Rotational and Circular Motion 30
- Atomic Spectra 30
- Alternating Current 30
- Force and Motion 30
Which expression gives the absolute gravitational potential energy of a mass m at a distance r from the centre of the Earth (mass M)?
Correct answer D. −GMm/r
A body is lifted from the Earth’s surface to a greater height. What happens to its absolute gravitational potential energy?
Correct answer D. It increases, becoming less negative
Advertisement
Power delivered by a force F to a body moving with velocity v is given by ____
Correct answer A. F·v
One horsepower is approximately equal to how many watts?
Correct answer C. 746 W
The kilowatt-hour (kWh) is a unit of which quantity?
Correct answer D. Energy
A box is pushed at constant speed along a rough floor. What becomes of the work done against friction?
Correct answer C. It is dissipated as heat
Why is the efficiency of a practical machine always less than 100%?
Correct answer A. Some input energy is lost as heat, sound and other forms
According to the work-energy principle, the net work done on a body equals ____
Correct answer C. the change in its kinetic energy
Advertisement
Two bodies have the same momentum but different masses. Which has the greater kinetic energy?
Correct answer A. The lighter body
A stone falls freely under gravity with no air resistance. Which statement is correct?
Correct answer D. The sum of its kinetic and potential energies stays constant
A porter carries a box on his head and walks along a level road at constant velocity. How much work does he do on the box against gravity?
Correct answer C. Zero
Which statement about conservative forces is correct?
Correct answer A. The work done by them is independent of the path taken
A force of 50 N pulls a trolley 10 m along the floor while acting at 60° to the direction of motion. How much work does it do?
Correct answer C. 250 J
What is the kinetic energy of a 2 kg ball moving at 3 m/s?
Correct answer C. 9 J
Advertisement
A 5 kg box is lifted vertically through 4 m. Taking g = 9.8 m/s², how much gravitational potential energy does it gain?
Correct answer D. 196 J
A crane lifts a 500 kg load through 12 m in 20 s at steady speed. Taking g = 9.8 m/s², what is its output power?
Correct answer B. 2940 W
How much work does a force do when it acts perpendicular to the displacement of a body?
Correct answer B. Zero
When is the work done by a force negative?
Correct answer B. When the force has a component opposite to the displacement
One joule is equivalent to which combination of base SI units?
Correct answer C. kg m² s⁻²