1) How much work is done in pushing a crate with a force of 50N over 10m? a) W = mg b) W = Fs c) W = F/d d) P = W/t e) F = ke 2) How much kinetic energy does an object with a mass of 20kg have when it travels at a speed of 32m/s? a) Ek = ½mv2 b) Ek = mv2 c) Ek = ½mv d) F = ke e) Ee = ½ke2 3) How much work does a 65kg climber do against gravity when she climbs 20m? a) Ek = ½mv2 b) Ep = mgh c) Ep = mg/h d) W = mg e) W = F/d 4) How much energy is stored in a spring (spring constant = 12N/m) when it is compressed by 3cm? a) Ek = ½mv2 b) Ep = mgh c) F = ke d) Ee = ½ke2 e) F = dk 5) How much energy is needed to heat 1.2kg of water from 23º to 65º? a) T = 1/f b) E = mgh c) E = mL d) E = mc2 e) E = mc∆T 6) How much power is transferred to a kettle in 100s if it is constantly supplied with 50J of thermal energy? a) P = Et b) P = E/t c) E = P/t d) efficiency = useful power out / total power in e) Ep = mc∆T 7) What is the efficiency of a motor that transfers 20J of electrical energy to 15J of kinetic energy? a) efficiency = useful power out / total power in b) efficiency = total power in / useful power out c) efficiency = total energy in / total energy out d) efficiency = useful energy out / total energy in e) efficiency = total energy in / useful energy out 8) Calculate the specific heat capacity of concrete. a) E = mc2 b) W = Fs c) c = ƒƛ d) E = mc∆T e) c = mE∆T 9) What is the radiation power transferred by a 55⁒ efficient lightbulb with a power rating of 20W? a) efficiency = useful power out / total power in b) efficiency = total power in / total power out c) P = Et d) P = E/t e) energy = useful energy out / total energy in 10) A 20kg weight has a gravitational potential energy of 500J at the moment is dropped from a height. What speed will it be travelling at just before it hits the ground (assume air resistance is negligible)? a) Ep = mgh b) W = Fd c) W = mg d) s = d/t e) Ek = ½mv2 11) A 60kg student exerts 1500J of chemical energy climbing the stairs at school. What is the height of the stairs? a) W = mg b) W = Fd c) Ep = mgh d) Ek = ½mv2 e) P = E/t 12) A bungee cord with a spring constant of 42N/m stores 50 000J of elastic potential energy when a man of mass 75kg is at the bottom of his jump. What is the extension of the bungee cord at this moment? a) F = ½ke b) Ek = ½mv2 c) Ee = ½ke2 d) W = mg e) W = Fd 13) How much energy is transferred to a 40W lamp that is switched on for 2 hours? a) P = Et b) E = Pt c) s = d/t d) P = I2R e) Q = It 14) A 0.5kg ball is thrown vertically upwards with an initial speed of 4m/s. What height does it reach? (assume air resistnace is negligible) a) W = mg then Ep = mgh b) Ep = mgh then W = Fs c) Ee = ½ke2 then Ep = mgh d) Ep = mgh then Ek = ½mv2 e) Ek = ½mv2 then Ep = mgh 15) How much power does a 40kg child exert when she runs up a 2.5m flight of stairs in 11s? a) Ep = mgh then P = E/t b) Ep = mgh then P = Et c) Ek = ½mv2 then P = E/t d) E = Pt then P = E/t e) Ep = mgh then Ek = ½mv2

Tema

Opções

Tabela de classificação

Alternar o modelo

Interativos

Restaurar arquivo salvo automaticamente: ?