1. State the energy changes taking place in the following cases: (1) A car moves up a
hilly road.(2) a stone projected vertically upward returns2. When we cut a log of wood with a saw it becomes warm, why?3. If an electric iron of 1200W is used for 30 minutes everyday, find electric energyconsumed in the month of April.
1. State the energy changes taking place in the following cases: (1) A car moves up a
(1) When a car moves up a hilly road considering a general case its KE is getting converted into PE and lose is KE is taking place due to deceleration since its moving not in favour of the acceleration due to gravity but against it.
(2) A stone projected vertically upward and then return to ground in such case there will be two parts of the motion: ascent (upward motion against the gravity KE--->PE) and descent(downward motion with the gravity PE--->KE).
(3) When we cut a log of wood with a saw it becomes warm because we are continuously doing the mechanical work on the log and during the process friction force is acting between the log and the saw while cutting it losing our energy and as a result log is getting some energy due to frictional force and gets warm.
(4) If an electric iron of P = 1200W is used for t = 30 mins or (30×60) 1800 sec everyday, find electric energy consumed in the month of April can be given using the formula:
P = E/t
⇒ E = Pt, Units will be joules!
(1) When a car moves up a hilly road considering a general case its KE is getting converted into PE and lose is KE is taking place due to deceleration since its moving not in favour of the acceleration due to gravity but against it.
(2) A stone projected vertically upward and then return to ground in such case there will be two parts of the motion: ascent (upward motion against the gravity KE--->PE) and descent(downward motion with the gravity PE--->KE).
(3) When we cut a log of wood with a saw it becomes warm because we are continuously doing the mechanical work on the log and during the process friction force is acting between the log and the saw while cutting it losing our energy and as a result log is getting some energy due to frictional force and gets warm.
(4) If an electric iron of P = 1200W is used for t = 30 mins or (30×60) 1800 sec everyday, find electric energy consumed in the month of April can be given using the formula:
P = E/t
⇒ E = Pt, Units will be joules!
