Physics problem help?

Question

Can someone help me solve this problem?

In bench pressing 105 kg, a weight lifter applies a force of 1049.3 N. How large is the upward acceleration of the weights during the lift?

Answer 1

In order for the lifter to keep the 105 kg weight in the air, he needs to fight gravity, which causes the weight to exert a force of 105kg(9.81 m/s^2) = 1030 N downwards. That leaves 1049.3-1030N to accelerate upwards. Using F=ma, you get a = 0.18 m/s^2.