
Mechanics Questions
Friction, Inclined Planes
Question 1
The system below is in equilibrium. Frictional forces can be neglected. 

a) 
Given that m_{2} = 0·2kg, calculate m_{1}. 
b) 
Calculate the gravitational potential energy gained by m_{1} if m_{2} is pushed down 0·3m. 
c) 
If m_{1} is removed and replaced by an object of mass 2m_{1}, calculate the acceleration of the system. 
d) 
Calculate the total kinetic energy of the system after 2s of acceleration (with the mass 2m_{1} in place and assuming that v_{o} = 0). 
Question 2
A body rests, without slipping, on a plane which is inclined at 30° to the horizontal. 
a) 
Draw a diagram showing the forces acting on the body. 
b) 
If the body has a mass of 2kg, calculate the magnitude of the force of friction acting on it. 
Question 3
An object of mass m = 5kg is being pulled up an inclined plane which is at 40° to the horizontal. The object is pulled at a constant speed of 0·8ms^{1} by a force which acts parallel to the inclined plane. The coefficient of friction between the object and the plane is 0·2. 
a) 
Draw a diagram showing the forces acting on the object. 
b) 
Calculate the magnitude of the force of friction acting on the object. 
c) 
Calculate the gain in g.p.e. when the object has moved 0·5m (measured parallel to the slope). 
d) 
Calculate the total work done in pulling the block 0·5m (measured parallel to the slope). 

