Question

A mechanic pushes a 5 kg load on a cart across a garage floor made of cement. The mechanic then pushes the same load across a grassy surface with the same force. He finds that the cart moves faster on the cement than on grass. What could be causing the change in the speed of the cart?"

a) Friction on grass is higher than on cement
b) Grass provides more traction than cement
c) Weight of the load is different on grass
d) Grass has higher density than cement

Answer 1

The change in the speed of the cart as it moves from cement to grass is likely caused by the difference in frictional forces between the two surfaces, with higher friction on the grassy surface leading to a slower movement.

Step-by-step explanation:

When a mechanic pushes a 5 kg load on a cart across different surfaces, the speed at which the cart moves is affected by several factors such as mass, surface texture, and friction. However, in this case, where the mechanic experiences a difference in speed while pushing the same load with the same force across cement and grass, the most likely reason for the change is friction. The greater resistance (friction) on the grassy surface compared to the cement surface causes the cart to move slower.

Frictional forces, like static and kinetic friction, play a significant role in how hard one has to push an object to move it and keep it in motion. Static friction is the force that needs to be overcome to start the motion of the cart, and it is usually higher than kinetic friction, which is the force that has to be overcome to keep the cart moving. Thus, on grass, the higher frictional forces mean that even when the static friction is overcome, the kinetic friction is enough to considerably slow down the cart compared to when it moves on the smoother cement surface.