Question

Pumping Iron. You overindulged on a delicious dessert, so you plan to work off the extra calories at the gym. To accomplish this, you decide to lift some weights. You hold a 5.00 kg weight in one hand, with your arm straight (unflexed) and held by your side. You then pivot your arm about the elbow joint until your arm is held at an angle of 60° above the horizontal. The distance from your elbow to the weight is 32.0 cm, and the centre of mass of the arm is 17.0 cm from the elbow joint. Let's assume that your mass is 70.0 kg, and the lower arm (including your hand) weighs 3.00% of your body weight. Also assume that your muscles are 20.0% efficient in converting the food energy they use up into mechanical energy, with the rest going into heat. If your dessert contained 380 kilocalories, how many of these lower arm raises must you do in order to work off these calories? Is it realistic to do these in one sitting?

Answer 1

To work off the calories from the dessert, you need to calculate the amount of work done by performing the lower arm raises. The work done can be calculated using the equation: Work = Force x Distance x cosθ.

Step-by-step explanation:

To work off the calories from the dessert, you need to calculate the amount of work done by performing the lower arm raises.

The work done can be calculated using the equation: Work = Force x Distance x cosθ.

In this case, the force is the weight being lifted, the distance is the length of the arm, and θ is the angle between the arm and the horizontal.

First, we need to calculate the force exerted by your arm.

The force can be calculated using the equation: Force = mass x acceleration. The mass of your arm is equal to the product of your body weight and the percentage weight of your lower arm, which is 3.00%.

The acceleration is the force of gravity, which is 9.8 m/s^2.

Once the force is calculated, you can use it in the work equation to find the amount of work needed to burn the calories from the dessert.

Divide the total calories by the work done per lower arm raise to find out how many lower arm raises you need to do.

Considering your body weight and the efficiency of your muscles, you can decide if it is realistic to do all the lower arm raises in one sitting.