Practice problems focused on calculating work done, energy transfers, and power in various physical systems.
For elastic collision, momentum and kinetic energy conserved: m1v1+m2v2=m1v1'+m2v2' and ½m1v1²+... per NCERT. Solving gives velocities matching 6 m/s. Inelastic loses energy. So option A is correct.
Ref: NCERT Class 11 Physics > Chapter 6: Work, Energy and Power > Topic: Energy Conservation and Friction
Initial K=12×1000×102=50000J. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 4 m/s. This satisfies dimensional consistency and physical conditions given, so option A is scientifically correct.
Ref: NCERT Class 11 Physics > Chapter 6: Work, Energy and Power > Topic: Energy Conservation and Friction
Potential energy mgh=7×10×3=210J. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 210 J. This satisfies dimensional consistency and physical conditions given, so option A is scientifically correct.
Ref: NCERT Class 11 Physics > Chapter 6: Work, Energy and Power > Topic: Energy Conservation and Friction
Work W=F·d=Fd cosθ per NCERT Chapter 6. Positive if force along displacement. Using given F, d, θ, calculation gives 0 J. Work-energy theorem W=ΔK confirms. So option B is correct.
Ref: NCERT Class 11 Physics > Chapter 6: Work, Energy and Power > Topic: Energy Conservation and Friction
Kinetic energy K=½mv² and potential U=mgh per NCERT. Energy conservation K+U=constant for conservative forces. Substituting m, v, h gives 180 J as energy, matching option B.
Ref: NCERT Class 11 Physics > Chapter 6: Work, Energy and Power > Topic: Energy Conservation and Friction
Power P=W/t=F·v per NCERT. Rate of doing work. With given force and velocity, P=Fv. Calculation yields 60 kW. Hence option B correctly represents power.
Ref: NCERT Class 11 Physics > Chapter 6: Work, Energy and Power > Topic: Energy Conservation and Friction
Work W=F·d=Fd cosθ per NCERT Chapter 6. Positive if force along displacement. Using given F, d, θ, calculation gives -2.9 J. Work-energy theorem W=ΔK confirms. So option B is correct.
Ref: NCERT Class 11 Physics > Chapter 6: Work, Energy and Power > Topic: Energy Conservation and Friction
Kinetic energy K=½mv² and potential U=mgh per NCERT. Energy conservation K+U=constant for conservative forces. Substituting m, v, h gives 12 J as energy, matching option A.
Ref: NCERT Class 11 Physics > Chapter 6: Work, Energy and Power > Topic: Energy Conservation and Friction
Work W=F·d=Fd cosθ per NCERT Chapter 6. Positive if force along displacement. Using given F, d, θ, calculation gives 22 J. Work-energy theorem W=ΔK confirms. So option C is correct.
Ref: NCERT Class 11 Physics > Chapter 6: Work, Energy and Power > Topic: Energy Conservation and Friction
Power P=W/t=F·v per NCERT. Rate of doing work. With given force and velocity, P=Fv. Calculation yields 86 kW. Hence option B correctly represents power.
Ref: NCERT Class 11 Physics > Chapter 6: Work, Energy and Power > Topic: Energy Conservation and Friction
Work W=F·d=Fd cosθ per NCERT Chapter 6. Positive if force along displacement. Using given F, d, θ, calculation gives 54 J. Work-energy theorem W=ΔK confirms. So option B is correct.
Ref: NCERT Class 11 Physics > Chapter 6: Work, Energy and Power > Topic: Energy Conservation and Friction
Work W=F·d=Fd cosθ per NCERT Chapter 6. Positive if force along displacement. Using given F, d, θ, calculation gives 680 J. Work-energy theorem W=ΔK confirms. So option B is correct.
Ref: NCERT Class 11 Physics > Chapter 6: Work, Energy and Power > Topic: Energy Conservation and Friction
