Help please? Physics?

1.)A cart loaded with bricks has a total mass of 17 kg and is pulled at constant speed by a rope. The rope is inclined at 23.7◦above the horizontal and the cart moves 11.5 m on a horizontal floor. The coefficient of kinetic friction between ground and cart is 0.4.The acceleration of gravity is 9.8 m/s2.What is the... show more 1.)A cart loaded with bricks has a total mass of 17 kg and is pulled at constant speed by a rope. The rope is inclined at 23.7◦above the horizontal and the cart moves 11.5 m on a horizontal floor. The coefficient of kinetic friction between ground and cart is 0.4.The acceleration of gravity is 9.8 m/s2.What is the normal force exerted on the cart by the floor?
Answer in units of N.

I used:
Normal Force=m(g)/(1+u*tan theta)
I got -88.66 which seems wrong to me...

2.)How much work is done on the cart by therope?Answer in units of kJ.

3.Note:The energy change due to friction is aloss of energy.What is the energy changeWfdue to fric-tion?Answer in units of kJ.

serious help please.
2 answers 2