Question

John is going to use a rope to pull his sister Laura across the ground in a sled through the snow. He is pulling horizontally with a constant force of 400 N. John and manages to get the sled going from 0 to 4 m/s in 5 s. The force due to friction on the sled is 310 N. What is the mass of Laura and the sled combined?

Answer 1

The mass of Laura and the sled combined is 887.5 kg

Step-by-step explanation:

The total force due to weight of Laura and friction on the sled can be calculated as follows;

`F_T = F_L+F_S`

= (400 + 310) N

= 710 N

From Newton's second law of motion, "the rate of change of momentum is directly proportional to the applied force.

`F_T = ((M_L+M_S)V)/(t)`

where;

`M_L` is mass of Laura and

`M_S` is mass of sled

Mass of Laura and the sled combined is calculated as follows;

`(M_L+M_S) = (F_T*t)/(V)`

given

V = Δv = 4-0 = 4m/s

t = 5 s

`(M_L+M_S) = (710*5)/(4)\\\\(M_L+M_S) = 887.5 kg`

Therefore, the mass of Laura and the sled combined is 887.5 kg