Question

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Quiz#4 Name: 1). Energy is defined as an ability of doing work a) True b) False c) Can's say 2). 1 Jule of energy corresponds to the work done a) 1 Nm b) 3 Nm c) 5 Nm 3). According to physics, does the earth do any work on moon a) No c) Can't say b) Yes 4). When we drop an object from a maximum height, initial kinetic energy is zero a) True b) False c) Undetermined 5). Find out the kinetic energy of an object of mass m = 10 Kg moving with the velocity 10 m/s 6). When we say energy is conserved, the sum of total energy is constant b) False a) True c) Can't say 7).A force is conservative if the net work done by the force on an object moving around any closed path is zero a) True c) Can't say b) False 8). For a spring, the spring force (F) and stiffness constant (k) are related as F, -kx a) True b) False c) Can't say 9). When an object moves in a frictional medium, energy converts into b) Electrical energy a) Thermal energy c) Solar energy 10). Power is defined as the rate of doing work, please choose which of the following defines the formula for power (P) а) Р- Fv Note F = force, d- distance, v= velocity, a acceleration, b) P Fd c) P Fa

Answer 1

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(1) True....answer.

Energy is the ability to do work.

2) 1Joule = 1N-m.

Option (a) is correct.

3)force exerted by earth on moon acts in radial direction point towards center of earth.and moon rotate about earth in circular orbit so displacement is always perpendicular to force.and hence work is Zero.

Option(a) is correct.

4) True... option (a) is correct.

5) kinetic energy=(1/2)×10×(10^2)=500J....answer.

6)True ... option (a) is correct.

7)True... option (a) is correct.

Conservative force work done is path independent.

8)true.option (a) is correct.

9)Thermal energy.option (a) is correct.

10)p=Fv