practice question


QUESTION 2

2.1. A person pushes a lawnmower of mass 15 kg at a constant speed in a straight line over a flat grass surface with a force of 90 N. The force is directed along the handle of the lawnmower. The handle has been set at an angle of 40° to the horizontal. Refer to the diagram below. 
2.1.1 Draw a labelled free-body diagram for the lawnmower.  (4)

2.1.2. Why is it CORRECT to say that the moving lawnmower is in equilibrium?  (1) 
2.1.3. Calculate the magnitude of the frictional force acting between the
lawnmower and the grass  (3) 

The lawnmower is now brought to a stop. 
2.1.4. Calculate the magnitude of the constant force that must be applied through the handle in order to accelerate the lawnmower from rest to 2 m∙s-1 in a time of 3 s. Assume that the frictional force between the lawnmower and grass remains the same as in QUESTION 2.1.3. (6)


2.2. Planet Y has a radius of 6 x 10^5 m. A 10 kg mass weighs 20 N on the surface of planet Y
Calculate the mass of planet Y.  (4)

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