Class 9 Practice Level 3 – Work and Energy- Set 2 Leave a Comment / By Gulam Hamza / July 11, 2024 Class 9 Practice Level 3 - Work and Energy- Set 2 Total questions: 15 1. A force of 150 N is applied at an angle of 60 degrees to the horizontal to pull a sled over a distance of 20 meters on a frictionless surface. Calculate the work done by the force. 1000 J 1500 J 2250 J 3000 J None 2. A car of mass 1500 kg is moving with a speed of 25 m/s. If the brakes are applied and the car comes to a stop in 10 seconds, what is the average power dissipated by the brakes? 18,750 W 28,125 W 37,500 W 46,875 W None 3. A motor lifts a 200 kg object to a height of 40 meters in 20 seconds. Calculate the power output of the motor. $ \displaystyle \left( {Take\text{ }g=10\,m/{{s}^{2}}} \right)$ 2000 W 4000 W 8000 W 16000 W None 4. A force of 120 N is applied at an angle of 45 degrees to move a box 15 meters. Calculate the work done by the force. 1272 J 1350 J 1500 J 1800 J None 5. A spring with a spring constant of 400 N/m is compressed by 0.25 meters. Calculate the potential energy stored in the spring. 10 J 12.5 J 15 J 25 J None 6. An electric motor exerts a constant force of 250 N to move an object at a constant speed of 5 m/s. Calculate the power developed by the motor 500 W 750 W 1000 W 1250 W None 7. A block of mass 6 kg is pulled up an incline plane of length 12 meters and height 8 meters by a force of 50 N acting parallel to the incline. Calculate the work done by the force. $ \displaystyle \left( {Take\text{ }g=10\,m/{{s}^{2}}} \right)$ 600 J 720 J 900 J 1000 J None 8. A 3 kg mass is attached to a spring with a spring constant of 200 N/m. The spring is compressed by 0.3 meters. Calculate the potential energy stored in the spring. 5 J 9 J 12 J 18 J None 9. A car engine provides a power output of 150 kW. If the car travels with a constant speed of 30 m/s, calculate the force exerted by the engine. 3000 N 3500 N 4000 N 5000 N None 10. An elevator lifts a 1000 kg load to a height of 50 meters in 25 seconds. Calculate the power output of the elevator motor..$\displaystyle \left( {Take\text{ }g=10\,m/{{s}^{2}}} \right)$ 1000 W 2000 W 4000 W 20,000 W None 11. A 0.8 kg ball is thrown vertically upwards with an initial velocity of 20 m/s. Calculate the maximum height reached by the ball. $ \displaystyle \left( {Take\text{ }g=10\,m/{{s}^{2}}} \right)$ 10 m 15 m 20 m 25 m None 12. A crane lifts a 750 kg load to a height of 30 meters in 20 seconds. Calculate the average power developed by the crane.$ \displaystyle \left( {Take\text{ }g=10\,m/{{s}^{2}}} \right)$ 7500 W 11,250 W 15,000 W 22,500 W None 13. A force of 90 N is applied at an angle of 30 degrees to the horizontal to move a 10 kg box over a distance of 10 meters. Calculate the work done by the force.$ \displaystyle \left( {Take\text{ }g\text{ }=\text{ }10\,m/{{s}^{2}}} \right)$ 450 J 650 J 779.4 J 900 J None 14. A 4 kg object is released from a height of 10 meters. Calculate its velocity just before it hits the ground.$ \displaystyle (Take\text{ }g=10m/{{s}^{2}}g)$ 10 m/s 12.65 m/s 14.14 m/s 15.81 m/s None 15. A person weighing 800 N climbs a 10-meter-high ladder in 5 seconds. Calculate the power developed by the person. 400 W 600 W 800 W 1600 W None 1 out of 15 Time's up