Question

piedOnS.Select the one Whhch 1S best im each case al An electrical heater voltage, double is operated and produces 10 joules of heat. If we double the the current and double the time the heater is operated, the heat in joules will be: (a) 10 (b)20 (c) 40 (d) 60 (e) 80 dhern stetion f poins . u ,ama t along the paths shown in the diagram below. DIAGRAM HERE The loss in gravitational potential energy is: (a) greatest over path I (b) greatest over path Ⅳ (c) the same over paths I, II, III, and Ⅳ (d) greatest for (e) greater for paths I and III than for paths II and IV paths I and Ⅱ than for paths III and IV . A 100 gm bullet attains a velocity of 500 m/s at the end of a 50 cm long rifle barrel. The average force in Newtons exerted on the bullet while in the barrel would be: (a) 2.5 x 107 (b) 5 x 104 (c) 500 (d) 2.5 x 103 (e) 2.5 × 104 4. A weight is attached to a spring and set in motion so as to vibrate up and down. Eventually the weight comes to rest because: (a) the total energy is not conserved in such a system (b) there is an increase in thermal energy when there is a change from kinetic to potential energy and vice versa (c) the spring increases its thermal energy but the sum of kinetic and potential energies of the spring and weight remains constant (d) when a spring is stretched its kinetic energy increases.

I need the answer for thses questions by detials.

Answer 1

a) H = 10J from joule'slawof heation gVen i'=2i,V'=2V and t' = 2t H'=8x10 e)H-80 m = 100g = 0.1kg v = 500m2 / s s 50cm 0.50m v'-' 500-0 250000m s 2s 2x0.5 F = ma = 0.1 × 250000 F 25000N e)|F-25x10 4) the motioncomesto rest dueto increaseinthermal energy due to theenergyconversion so the answer s b)there is an increase in thermal energy when thereisa chenge in kinetic to potential energy and vice -versa