Practice Questions
(Density, weight, force and energy)
1
The figure below shows a rocket about to transport a large mirror into orbit around the Earth.
(a)
When the rocket is launched, the force exerted on the rocket is 12 000 000 N vertically
upwards.
Calculate the resultant force on the rocket.
State the direction of the resultant force.
(b)
2
Describe the motion of the rocket as it leaves the Earth.
The rocket is powered by a fuel. The fuel is a store of chemical potential energy.
As the rocket moves upwards, large flames can be seen coming out of the back of the rocket.
The ground crew wear ear protection for their hearing as the rocket rises off the ground.
Use this information to identify three forms of energy resulting from the launch of the rocket.
Use this information to identify three forms of energy resulting from the launch of the rocket.
1. ................................................................................................................................... energy
2. .................................................................................................................................. energy
3. .................................................................................................................................. energy
3
The boat is travelling at a constant speed across the surface of the sea.
The figure below shows four forces, P, Q, R and S, acting on the boat.
(a)
State the letter of the force driving the boat forward.
…………….
(b)
Some of these forces are equal to each other.
Place a tick in the box next to each pair of forces that must be equal in magnitude to
each other.
(c)
The motor boat is driven by a gasoline (petrol) engine that turns the propeller.
Complete the sequence of useful energy changes that take place from the gasoline to
the motion of the boat.
............................................................ energy in the gasoline
thermal energy in the engine
……………………………………… energy of the propeller
……………………………………… energy of the moving boat.
(d)
4
The boat takes 5.0 minutes to travel 960 metres.
Calculate the speed of the boat in metres per second.
The figure below shows a cylinder made of solid copper.
The cylinder has a:
(a)
•height of 25 cm
•radius of 10 cm
•mass of 70 000 g.
Show that the volume of the copper cylinder is 7850 cm3.
π = 3.14
(b)
Use the information above to calculate the density of copper in g/cm3.