FORCE -DPP3 (ICSE )

If no external force acts on a moving body, then:

• It will continue to move with the same speed along a straight line

• It will remain at rest forever

• It will stop moving

• It will not be affected at all

If action and reaction are equal and opposite, then how does motion occur?

• It is because action and reaction forces act on the same body.

• It is because action and reaction forces do not act simultaneously on the same body.

• It is because action and reaction forces act simultaneously on different bodies.

• It is independent of the action and reaction forces.

An archer shoots an arrow. Consider the action force to be bowstring against the arrow. What will be the reaction force?

• Arrow pushing against bowstring

• Weight of the arrow

• Air resistance against the bow

• Grip of the archer's hand on the bow

Which of the following is/are false? (i) Centrifugal force acts in a direction opposite to that of centripetal force. (ii) centripetal and centrifugal forces are equal in magnitude. (iii) Centripetal force and centrifugal forces are not equal in magnitudes. (iv) centripetal force is a pseudo force.

• (iii) and (iv)

• (ii) and (iv)

• Only (iii)

• Only (iv)

A nut is opened by a wrench of 10 cm. If the least force required is 10 N, find the moment of force needed to turn the nut.

• 0.5 Nm

• 1 N cm

• 0.5 N cm

• 1 N m

Two forces each of magnitude 2N act vertically upward and downward respectively on two ends of a uniform rod of length 1m, freely pivoted at its centre. Determine the resultant moment of forces about the mid-point of the rod.

• 1Nm

• 6Nm

• 2Nm

• 4Nm

Two forces F₁ and F₂ are applied on a circular body such that moment of couple is 9 Nm in CWD. Calculate the radius of circular body.

• 10cm

• 60cm

• 30cm

• 40cm

A uniform wooden beam, 80 cm long and weighing 250 gf, is supported on a wedge as shown in the figure. Calculate the greatest weight which can be placed on end A without causing the beam to tilt.

• 100 gf

• 375 gf

• 560 gf

• 750 gf

A mechanic can open a nut by applying 120 N force while using a lever of 50 cm length. How long should the handle be, if he wishes to open, it by applying a force of only 40 N?

• 1

• 2

• 1.5

• 2.5

A uniform metre scale is balanced at 60 cm mark, when weights of 5 gf and 40 gf are suspended at 10 cm mark and 80 cm mark respectively. Calculate the weight of the metre scale.

• 25gf

• 15gf

• 37gf

• 55gf