topic 2 mechanics

A ball is tossed vertically upwards with a speed of 5.0 m s⁻¹. After how many seconds will the ball return to its initial position?

• 0.5s

• 1s

• 1.5s

• 2s

A car moves north at a constant speed of 3 m s⁻¹ for 20 s and then east at a constant speed of 4 m s⁻¹ for 20 s. What is the average speed of the car during this motion?

• 7.0 m s⁻¹

• 5.0 m s⁻¹

• 3.5 m s⁻¹

• 2.5 m s⁻¹

A body moves on a straight line. The graphs show the variation of displacement with time.Which graph shows motion with negative acceleration?

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A ball is thrown from the top of a cliff. The initial magnitude of the velocity of the ball at time t =0 is V. The ball hits the sea at time t = T. Air resistance is negligible.

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The efficiency of an electric motor is 20 %. When lifting a body 500 J of energy are wasted.What is the useful work done by the motor?

• 125

• 120

• 105

• 100

In which diagram are the forces balanced?

• A

• B

• C

• D

A Weight W is suspended from two strings. What is the weight?

• 10 N

• 20 N

• 30 N

• 34.6 N

Which of the following statements about the friction between the two surfaces are true?

• The coefficient of dynamic friction has a range of values

• The coefficient of static friction has a range of values

• dynamic friction has a range of values

• Static friction can have a range of values

Three blocks are pulled across a smooth surface by a force of 12 N. What is the tension T in the rope?

• 2 N

• 4 N

• 8 N

• 10 N

A small explosion is used to separate a space capsule from its rocket, after the rocket fuel is used up.

Which statement(s) about the process are true?

• the total momentum of the system increases

• the total kinetic energy of the system increases

• the total momentum of the system remains constant

• the total kinetic energy of the system remains constant