Class 9 Practice Level 3 – Force and Laws of Motion – Set 1 Leave a Comment / By Gulam Hamza / July 8, 2024 Class 9 Practice Level 3 - Force and Laws of Motion - Set 1 Total questions: 15 1. A force of 100 N is applied at an angle of 30Â° to the horizontal on a 20 kg object. What is the horizontal component of the force? 50 N 86.6 N 100 N 43.3 N None 2. A 50 kg cart is pushed with a force of 200 N at an angle of 45Â° to the horizontal. What is the acceleration of the cart in the horizontal direction? $ \displaystyle {2\text{ }m/s{}^\text{2}}$ $\displaystyle {2.83\text{ }m/s{}^\text{2}}$ $ \displaystyle {3.16\text{ }m/s{}^\text{2}}$ $ \displaystyle {4\text{ }m/s{}^\text{2}}$ None 3. A car of mass 1000 kg moving at 20 m/s comes to a stop over a distance of 50 m. What is the average force exerted on the car? 400 N 800 N 2000 N 4000 N None 4. A stone of mass 0.5 kg is tied to a string and rotated in a circle of radius 2 m with a speed of 4 m/s. What is the tension in the string? 2 N 4 N 8 N 16 N None 5. Two ice skaters, each of mass 50 kg, push off from each other. One skater moves at 3 m/s. What is the velocity of the other skater? 1 m/s 2 m/s 3 m/s 4 m/s None 6. A ball of mass 0.2 kg moving at 5 m/s is brought to rest in 0.1 seconds. What is the average force exerted on the ball? 1 N 5 N 10 N 15 N None 7. The gravitational force between two masses 5 kg and 10 kg separated by a distance of 2 m is: $ \displaystyle {6.67\times {{{10}}^{{-11}}}\,N}$ $ \displaystyle {1.67\times {{{10}}^{{-10}}}\,N}$ $\displaystyle {8.34\times {{{10}}^{{-10}}}\,N}$ $\displaystyle {5.0\times {{{10}}^{{-10}}}\,N}$ None 8. A rocket with a mass of 500 kg is subjected to a force of 10,000 N. What is the rocket's acceleration? 10 m/sÂ² 15 m/sÂ² 20 m/sÂ² 25 m/sÂ² None 9. A block is pushed up a 30Â° incline with a force of 200 N parallel to the incline. If the block moves 5 m along the incline, what is the work done by the force? 500 J 700 J 800 J 1000 J None 10. A 2 kg object moving at 3 m/s collides elastically with a 1 kg object at rest. After the collision, the 2 kg object moves at 1 m/s. What is the velocity of the 1 kg object? 1 m/s 2 m/s 4 m/s 6 m/s None 11. A 600 kg rocket accelerates upwards at 15 m/sÂ². What is the force exerted by the gases expelled by the rocket? 9000 N 6000 N 12000 N 15000 N None 12. A car of mass 1000 kg moving at 10 m/s applies brakes and comes to a stop in 5 seconds. What is the frictional force applied by the brakes? 2000 N 1000 N 5000 N 4000 N None 13. A spring with a spring constant of 400 N/m is compressed by 0.2 m. What is the potential energy stored in the spring? 2 J 4 J 6 J 8 J None 14. A 10 kg box is at rest on a horizontal surface. The coefficient of static friction is 0.5. What is the maximum force that can be applied horizontally before the box starts to move? 10 N 20 N 30 N 50 N None 15. A 0.1 kg tennis ball moving at 30 m/s is struck by a racket, causing it to reverse direction and travel at 20 m/s. If the contact time is 0.01 seconds, what is the average force exerted by the racket? 500 N 100 N 200 N 300 N None 1 out of 15 Time's up