Deck 10: Linear Momentum and Impulse

Question 1

Answer 1

Question 2

(a) A rectangular metal bar has a width of 16 mm and can support a maximum compressive stress of 15 MPa; determine the minimum breadth of the bar when loaded with a force of 6 kN. (b) If the bar in (a) is 1.5 m long and decreases in length by 0.18 mm when the force is applied, determine the strain and the percentage strain.

Answer 2

Question 3

A wire is stretched 2.50 mm by a force of 400 N. Determine the force that would stretch the wire 3.50 mm, assuming that the elastic limit is not exceeded.

Answer 3

Question 4

A copper tube has an internal diameter of 140 mm and an outside diameter of 180 mm and is used to support a load of 4 kN. The tube is 600 mm long before the load is applied. Determine, in micrometres, by how much the tube contracts when loaded, taking the modulus of elasticity for copper as 96 GPa.

Question 5

Determine the momentum of a lorry of mass 10 tonnes moving at a velocity of 81 km/h.

Question 6

A ball of mass 50 g is moving with a velocity of 4 m/s when it strikes a stationary ball of mass 25 g. The velocity of the 50 g ball after impact is 2.5 m/s in the same direction as before impact. Determine the velocity of the 25 g ball after impact.

Question 7

A force of 24 N acts on a body of mass 6 kg for 150 ms. Determine the change in velocity.

Question 8

The hammer of a pile-driver of mass 800 kg falls a distance of 1.0 m on to a pile. The blow takes place in 20 ms and the hammer does not rebound. Determine (a) the velocity of impact (b) the momentum lost by the hammer (c) the average applied force exerted on the pile by the hammer.