Work, Energy and Power Test

Result

Work, Energy and Power Test - 1

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Weekly Quiz Competition

Question 1
1 / -0

The work done in pulling up a block of wood weighing 2 kN for a length of 10 m on a smooth plane inclined at an angle of 15° with the horizontal is ________. (sin 15° = 0.2588)

A
4.36 kJ

B
5.17 kJ

C
8.91 kJ

D
9.82 kJ
Question 2
1 / -0

A crane is used to lift 10000 kg of coal from a mine 100 m deep. If the time taken to lift coal by the crane is 1 hour, then what is the power of the driving mechanism of the crane?
(Efficiency of the crane is 80%, g = 9.8 m/s²)

A
8000 W

B
6408 W

C
3403 W

D
1833 W
Question 3
1 / -0

The scalar product of two vectors A and B in terms of the magnitudes and angle θ is

A
|A||B|cosθ

B
|A||B|cotθ

C
|A||B|sinθ

D
|A||B|tanθ

Solution

The scalar product of two vectors can be constructed by taking the component of one vector in the direction of the other and multiplying it times the magnitude of the other vector. This can be expressed in the form

A⃗ .B⃗ =|A||B|cosθ
Question 4
1 / -0

The scalar product of two vectors A and B is

A
a complex number

B
a scalar

C
vector

D
a tensor

Solution

Scalar product means dot product and dot product of 2 vectors gives a scalar , example dot product of force and displacement gives work which is scalar
Question 5
1 / -0

A 1 kg ball moving at 12 m/s collides head-on with a 2 kg ball moving in the opposite direction at 24 m/s. What is the velocity of each ball after the impact if the coefficient of restitution is 2/3 ?

A
v₁ = – 28 m/s, v₂ = – 4 m/s

B
v₁ = 20 m/s, v₂ = 2 m/s

C
v₁ = – 30 m/s, v₂ = – 18 m/s

D
v₁ = – 20 m/s, v₂ = – 4 m/s