An athlete with a mass of 62 kg jumps and lands
on the ground on his feet. Th e ground exerts a total
force of 1.1 x 10 ^ 3 N [backward 55°up] on his feet.
Calculate the acceleration of the athlete.

Do you know what the laws are?

Are you studying impulsive forces now?

F=ma therefore a=F/m, break down the components of the force vector and solve it.

backward 55°up

 

What do you mean by this? Do you mean that in reference to a perpendicular line on the ground, let's say x = 0, the force makes an angle of 55° to the left of that line?

After finding the x and y components of the force on his feet, find the force of gravity from his mass and subtract it from the F1y component. Now you can find acceleration