Mock Test 1 — Work, Energy and Power

A particle moves under $F = (3\hat{i} + 4\hat{j})$ N along displacement $(2\hat{i} + 3\hat{j})$ m. Work done:

The KE of a body becomes $9$ times. Its momentum becomes:

A spring is cut into 3 equal parts. New spring constant of each part:

A man pulls a $10$ kg crate at $30^\circ$ above horizontal by $50$ N over $5$ m on smooth surface. Work done by him:

Two bodies of masses $m$ and $4m$ have equal KE. Ratio of their momenta:

A body of mass $2$ kg at rest is acted on by a constant power $4$ W. Velocity after $2$ s:

A bullet of $20$ g penetrates $10$ cm in a wooden block. To penetrate $40$ cm with the same block, its velocity should be multiplied by:

A spring with force constant $200$ N/m is compressed by $5$ cm. The potential energy stored:

A pump delivers $10$ litres of water per second at $5$ m/s through a horizontal pipe. Power:

A bullet hits a stationary block, embeds in it. The maximum loss in KE is when:

A spring of $k = 1000$ N/m stretched by $10$ cm. Energy stored (in J):

A body of $2$ kg is dropped from $10$ m. KE just before hitting ground (J, $g = 10$):

A bullet of $30$ g at $100$ m/s embeds in a $1.47$ kg block. Common velocity (m/s):

Assertion (A): Work-energy theorem holds for non-conservative forces too. Reason (R): It states that the net work done by all forces equals the change in KE.

Assertion (A): Total mechanical energy is conserved only when conservative forces act. Reason (R): Non-conservative forces convert mechanical energy to other forms.