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b) A man who has a mass of 80 kg can run up a flight of stairs of 20 steps, in 5 seconds. Given that each step is 20 cm high, how much power does the man use to run up the flight of stairs?
0.1 kg aluminum calorimeter contains 0.2 kg water at 70.6 °C. It is found that the temperature of the calorimeter and water drops to 20°C in 15 minutes. What is the rate of heat flow to the atmosphere?
Merlinda is heating 2-kg water initially at 6.5 °C using a 100-Watt solar-powered heater. How long will it take (in seconds) to reach the boiling point?
a) An object of mass 3 kg is dropped from the roof of a two-storey house and reaches the ground with a speed of 10 m/s. Neglecting friction, calculate:
i. the kinetic energy of the object when it reaches the ground.
ii. the potential energy of the object when it is on the roof.
iii. the height of the roof.
iv. the total mechanical energy of the object when it is 1 m above the ground.
A KTM commuter train travels between two stations, A and B. The train starts from rest from station A and accelerates at a constant rate for 0.5 km until it reaches a speed of 30 m/s. It then travels at this constant speed for T s before decelerating at a constant rate of 1.5 m/s2 and coming to rest at station B. Figure 1 shows the velocity-time graph of the train’s journey between the two stations. Determine the value of T if the distance between the two stations 6 km. Calculate also the total time taken for the whole journey.
a 20.0 kg box is pulled horizontally 9.0 m along a level frictionless surface at a constant velocity. How much work is done on the box?
The angular position of a swinging door is described by θ(t)= (5.00+ 2.00t³) rad
Determine the angular position, angular speed, and angular acceleration of the door at t=3.0s.
A car approaches a stationary police car at 36 m/s. The frequency of the siren (relative to the police car) is 500 Hz. What is the frequency (in Hz) heard by an observer in the moving car as he approaches the police car? (Assume the velocity of sound in air is 343
m/s.)
an inclined plane of angle 20, has a spring of force constant k=500 N/m, fastened securely at the bottom so that the spring is parallel to the surface,a block of mass m =2.50 kg is placed on the plane at a distance d=0.3m from the spring. From this position ,the block is projected downwards towards the spring with speed v=0.750 m/s. By what distance is the spring compressed when the block momentarily comes to rest ?
QUESTION 1
a) Estimate the volume of the earth in m3 by assuming that its radius is 6400 km.
b) A car accelerates from zero to 20 m/s in 5 s.
i.
Calculate the acceleration of the car.
ii.
If the acceleration is assumed to be constant, how far will the car travel in 15 s?
iii.
Calculate the speed of the car after 15 s.
