PHYSICS SEMINAR

Figure 2 shows the graph of velocity, v against time, t, for the movement of a piece of rock thrown vertically upwards.

What was the height reached by the stone when its velocity was 15 ms-1?

• 10.00 m

• 11.25 m 

• 33.75 m

• 41.25 m

Figure 3 shows a car of mass 2000 kg that broke down and has to be towed by a lorry in a straight line at an acceleration of 1 ms-2 .

If the frictional force acting on the car is 50 N , what is the tension in the rope, T ?

• 1 950 N

• 2 000 N

• 2 050 N

• 2 500 N

Two satellites X and Y of the Earth have masses m and 2m and orbits radii r and 2r respectively as shown in the diagram.

The speeds of the satellite are VX and VY. which of the following correctly states VX and VY?

• Vx = √2  Vy                      

• B   Vx = Vy/√2

• Vx = 2Vy

• D  Vx = 4Vy

The escape velocity from the surface of the Earth is v. What is the escape velocity from a height h = 2R, where R is the radius of the Earth?

• v/√3        

            

• v/√2

• √2  v

• √3  v

Figure shows an arrangement of four resistors. When the points P and Q are connected to a circuit, the effective resistance is R1.

      When the points X and Y are connected to a circuit, the effective resistance is R2.

 What is the ratio of R1:R2?

• 1:1

• 1:2 

• 3:4

• 8:9

• 9:8