A-Level AQA Physics Equations of Motion: Figure 8 shows a model of a syst

Question

Figure 8 shows a model of a system being designed to move concrete building blocks from an upper to a lower level.

The model consists of two identical trolleys of mass M on a ramp which is at $35^{\circ}$ to the horizontal. The trolleys are connected by a wire that passes around a pulley of negligible mass at the top of the ramp. The trolley is released and accelerates to the bottom of the ramp where it is stopped by a flexible buffer. The blocks are unloaded from trolley A and two blocks are loaded onto trolley B that is now at the top of the ramp. The trolleys are released and the process is repeated.

Figure 9 shows the side view of trolley A when it is moving down the ramp.

**0 6.1**
The tension in the wire when the trolleys are moving is $T$.

Draw and label arrows on Figure 9 to represent the magnitudes and directions of any forces and components of forces that act on trolley A as it travels down the ramp.

**0 6.2**
Assume that no friction acts at the axle of the pulley or at the axles of the trolleys and that air resistance is negligible.

Show that the acceleration $a$ of trolley B along the ramp is given by

a = \frac{mg \sin 35^{\circ}}{M + m}

**0 6.3**
Compare the momentum of loaded trolley A as it moves downwards with the momentum of loaded trolley B.

**0 6.4**
In practice, for safety reasons there is a friction brake in the pulley that provides a resistive force to reduce the acceleration to 25% of the maximum possible acceleration.

The distance travelled for each journey down the ramp is 9.0 m.

The following data apply to the arrangement.

Mass of a trolley M = 95 kg
Mass of a concrete block m = 30 kg

Calculate the time taken for a loaded trolley to travel down the ramp.

**time =** $\_

**0 6.5**
It takes 12 s to remove the blocks from the lower trolley and reload the upper.

Calculate the number of blocks that can be transferred to the lower level in 30 minutes.

Figure 8 shows a model of a system being designed to move concrete building blocks from an upper to a lower level - AQA - A-Level Physics - Question 6 - 2017 - Paper 1

Worked Solution & Example Answer:Figure 8 shows a model of a system being designed to move concrete building blocks from an upper to a lower level - AQA - A-Level Physics - Question 6 - 2017 - Paper 1

The tension in the wire when the trolleys are moving is $T$.

Assume that no friction acts at the axle of the pulley or at the axles of the trolleys and that air resistance is negligible.

Compare the momentum of loaded trolley A as it moves downwards with the momentum of loaded trolley B.

Calculate the time taken for a loaded trolley to travel down the ramp.

Calculate the number of blocks that can be transferred to the lower level in 30 minutes.

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