CAIE A-Level Physics AS 5.1.7 P Fv and Use It to Solve Problems Questions

Explain and apply gravitational potential energy and kinetic energy in energy-transfer problems.

Exam points

Explain and apply gravitational potential energy and kinetic energy in energy-transfer problems.

[Maximum number: 2]

A car travels in a straight line up a slope, as shown in Fig. 3.1.

Fig. 3.1

The car has mass 850 kg and travels with a constant speed of $9.0 \mathrm{~ms}^{-1}$ . The car's engine exerts a force on the car of 2.0 kN up the slope.

A resistive force $F_{\mathrm{D}}$ , due to friction and air resistance, opposes the motion of the car.
The variation of $F_{\mathrm{D}}$ with the speed v of the car is shown in Fig. 3.2.

Fig. 3.2

Show that the power output of the car is $1.8 \times 10^{4} \mathrm{~W}$ .

P=F v
$=2.0 \times 10^{3} \times 9.0=1.8 \times 10^{4} \mathrm{~W}$

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CAIE A-Level Physics AS 5.1.7 P Fv and Use It to Solve Problems Questions question 1