eCoaching | Online Home Tutors & Teachers
Question Options
Which list contains only scalar quantities? acceleration, displacement, velocity, distance, force, speed, force, length, time, length, mass,
A car travels along a road. The driver stops the car by pushing his foot down on the brake pedal. What does not change if he pushes harder on the brake pedal? the braking distance, the braking force, the stopping distance, the thinking distance
What affects the stability of an object? only its base area, only its base area and the location of its centre of mass, only its weight and
A person of weight 600 N at the bottom of a mountain climbs to the top. The gravitational field strength changes from 10.00 N / kg at the bottom to 9.97 N / kg at the top. His mass is unchanged as he climbs. What are his mass and his weight at the top of the mountain? mass at top of mountain / kg 60.0 weight at top of mountain / N 598, mass at top of mountain
The tubes inside solar heating panels use the Sun’s radiation to warm water. Why are the tubes painted black? Black surfaces absorb radiation well., Black surfaces conduct heat well., Black surfaces emit radi
A liquid evaporates rapidly. Why does this cause it to cool? Air molecules remove heat by contact with the liquid surface., Energy is lost by convection current
What is caused by the thermal expansion of a substance when heated? a decrease in the resistance of a tungsten-filament lamp when switched on, a rise in the pressure o
The energy output of a generator depends on its efficiency and the energy input. Which set of values is correct? efficiency 0.1 energy input / MJ 50 energy output / MJ 25, efficiency 0.2 energy in
When one radium nucleus decays, its mass decreases by 8.8 × 10–30 kg. How much energy is equivalent to this loss in mass? (speed of light c = 3.0 × 10 ^ 8 m / s) 6.8 × 10–42 J, 2.6 × 10–21 J , 4.0 × 10–13 J, 7.9 × 10–13 J
During a thunderstorm, there is an interval of 1.70 s between an observer seeing the lightning and hearing the thunder. The speed of sound is 340 m / s. What is the distance between the observer and the storm? 100 m, 200 m, 578 m, 1160 m
Which pair of emissions travels with the same speed in air? alpha-particles and gamma-rays, gamma-rays and infra-red waves, infra-red waves and sound waves, s
A ray of light strikes the surface of a glass block at an angle of incidence of 45°. The refractive index of the glass is 1.5. What is the angle of refraction inside the block? 28 °, 30 °, 45 °, 67 °
An object is viewed through a concave (diverging) lens. What is the correct description of the image formed? real, inverted, magnified, real, upright, diminished, virtual, inverted, magnified, virtual, upri
Many electrical appliances have metal cases. To prevent the case from becoming ‘live’, with the possibility of an electric shock, the earth wire of the electric cable is attached to the case. How does the earth wire prevent an electric shock? It allows a current to flow to earth, so that the appliance continues working., It allows a large c
Electric power cables transmit electrical energy over large distances using a high voltage, alternating current. What are the advantages of using a high voltage and of using an alternating current? a higher current is produced in the cable the resistance of the cable is reduced, a highe
What does not alter the size of the turning effect on the coil of an electric motor? the direction of the current in the coil, the number of turns in the coil, the size of the current
15 / 7 N is a nuclide of nitrogen .How many electrons are there in a neutral atom of 15 / 7 N ? 7, 8, 15, 22