1. A physics student does a work on a 2.5 kg curling stone by exerting 50 N of force horizontally over a distance of 2 m. Calculate the work done by the student on the curling stone. 2. Calculate the kinetic energy of the following objects. (a) A man of mass 50 kg running at a speed of 20m/s (b) A200 g of bullet fired at a speed of 300m/s (c) A car of mass 1000 kg travelling at 80 meter per second 3. Calculate (a) The potential energy of 10 kg stone placed at a height of 10m above the ground. (b) The position of the 10 kg stone if it possesses a potential energy of 400 J. 4. A crane is capable of doing 1.5times 10^5 of work in 10 seconds. What is the power of the crane in watts?

1. Work done is calculated by multiplying the force applied in the direction of motion by the distance the object moves. Work = Force x Distance. In this case, Work = 50 N x 2 m = **100 Joules**.<br /><br />2. Kinetic energy is calculated using the formula KE = (1/2)mv², where m is mass and v is velocity.<br /><br /> **(a)** KE = (1/2) * 50 kg * (20 m/s)² = **10,000 Joules**<br /><br /> **(b)** First, convert the mass to kilograms: 200 g = 0.2 kg. Then, KE = (1/2) * 0.2 kg * (300 m/s)² = **9,000 Joules**<br /><br /> **(c)** KE = (1/2) * 1000 kg * (80 m/s)² = **3,200,000 Joules**<br /><br />3. Potential energy is calculated using the formula PE = mgh, where m is mass, g is the acceleration due to gravity (approximately 9.8 m/s²), and h is height.<br /><br /> **(a)** PE = 10 kg * 9.8 m/s² * 10 m = **980 Joules**<br /><br /> **(b)** To find the height, rearrange the formula: h = PE / (mg). h = 400 J / (10 kg * 9.8 m/s²) = **approximately 4.08 meters**<br /><br />4. Power is the rate at which work is done, calculated as Power = Work / Time. In this case, Power = (1.5 x 10⁵ J) / 10 s = **15,000 Watts** or **15 kW**.<br />